https://orcid.org/0000-0002-0161-2952
Abstract
Contact tracing has been a crucial public health strategy for breaking infectious diseases chains of transmission. Although many resources exist for disease outbreak management none address the rationale of contact tracing. This comprehensive review aims to evaluate contact tracing strategies, their effectiveness, and health systems governance across various diseases to inform a disease-agnostic contact tracing guideline. This systematic review was registered with PROSPERO (ID: CRD42023474507) and follows Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Descriptive and interventional studies in the six official United Nations languages were included, excluding modelling studies and animal-to-human transmission. An electronic search was conducted in Embase, Medline, Medline-in-process, and Cochrane libraries from inception to September 2023. The revised Cochrane Risk of Bias Tool and the Risk of Bias in Non-Randomized Studies of Interventions were used for bias assessment. The search yielded 378 studies, primarily from Europe (29.6%) and North America (21.6%) and focusing on diseases such as the coronavirus disease (COVID-19) (47.4%) or tuberculosis (26.7%). 244 (64.5%) studies addressed contact tracing definitions, commonly based on physical proximity, including duration of contact and sexual partnerships (47.6%) and household exposure (27%). Effectiveness was examined in 330 (87.3%) studies, showing variation across diseases and contexts, with only five studies evaluating epidemiological impacts. Socio-cultural aspects were covered in 166 (43.9%) studies, revealing that stigma and public trust may affect the adherence to contact tracing. Health systems governance was discussed in 278 (73.5%) studies, emphasising the need for coordination among international organisations, national governments, and local health authorities, alongside a sustained and adequately supported workforce. This review provides critical insights into optimising contact tracing strategies. Effective contact tracing requires robust health systems governance, adequate resources, and community involvement. Future research should focus on establishing standardised metrics for comparative analysis and investigating the impact of contact tracing on disease incidence and mortality.
Figures
Citation: Guy D, Kodjamanova P, Woldmann L, Sahota J, Bannister-Tyrrell M, Elouard Y, et al. (2025) Contact tracing strategies for infectious diseases: A systematic literature review. PLOS Glob Public Health 5(5): e0004579. https://doi.org/10.1371/journal.pgph.0004579
Editor: Bashar Haruna Gulumbe, Federal University Birnin Kebbi, NIGERIA
Received: September 23, 2024; Accepted: April 9, 2025; Published: May 9, 2025
Copyright: © 2025 Guy et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: No data were reported in the study. All methods and metadata required to replicate the results of our review are contained in the article.
Funding: The authors received no specific funding for this work.
Competing interests: The authors have declared that no competing interests exist.
Introduction
Rationale
Contact tracing has been a longstanding public health strategy to break infectious disease chains of transmission. It has been documented as early as in the 17th century for bubonic plague and was first operationalised in the beginning of the 20th century to fight syphilis outbreaks [1–3]. Contact tracing continues to be used today to halt the spread of high priority epidemic-prone diseases including Ebola virus disease, measles, among others [4]. The unprecedented global response to the coronavirus disease (COVID-19) pandemic highlighted the need for internationally agreed upon standards for contact tracing [5].
The scale and volume of cases and contact persons during an epidemic or pandemic can overwhelm healthcare systems and public health agencies. The sheer magnitude of identifying, contacting, and monitoring many individuals necessitates substantial resources and coordination, often across varying levels of governments [6]. Additionally, the management of sensitive health data introduces challenges in terms of collecting and storing personal information while maintaining privacy and security, especially with the use of digital tools and databases [6].
Successful contact tracing heavily relies on community engagement, which can be hindered by consequences associated with being identified as a contact person and the interpretation and consequences of the use of contact tracing information [6–9]. Furthermore, the evolving nature of infectious diseases may require rapid adaptation of contact tracing protocols to address new variants and changing transmission dynamics [6]. Ethical considerations play a crucial role in balancing public health protection with individual rights and privacy, while efficiently and optimally deploying resources is essential for effective contact tracing efforts [6].
Despite its importance in controlling the spread of infectious diseases, contact tracing strategies are not without potential harms. Concerns include infringement on personal privacy and data security, stigmatisation and discrimination of individuals, risks associated with inaccurate results, and the resource-intensive nature of contact tracing [10–13].
Previous systematic reviews have assessed contact tracing for specific diseases or geographical contexts [1,6,14–23]. With evolving guidelines, technological advancements, and cultural variations, understanding optimal strategies remains a global public health challenge. Notably, key evidence gaps persist regarding the most effective design and implementation methods. Thus, a comprehensive review of contact tracing strategies and their effectiveness across diseases with diverse transmission modes and outbreak scenarios is essential for enhancing preparedness against endemic, epidemic, and emerging infectious diseases.
Objectives
The absence of comprehensive global contact tracing strategy, guidelines and standard operating procedures was stressed during a consultation organised by the Global Outbreak Alert and response Network in June 2020 [24]. Although many resources exist for vertical program disease management, outbreak containment, and response none address the overall rationale of contact tracing and optimal strategies, nor give proper attention to the truly multisectoral nature of this public health intervention. This review was therefore commissioned by the World Health Organization (WHO) as part of the development of a disease-agnostic guideline on contact tracing primarily intended for national and subnational decision makers to develop guidance and implement actions to respond to outbreaks [25]. The review aimed to synthesise evidence on contact tracing strategies, regardless of disease area, offering insights into strategies, structures, impact measures, and resource requirements. As such, the review aspired to answer the following questions:
- What are the different contact tracing strategies used in controlling the spread of infectious diseases?
- How is effectiveness for contact tracing strategies defined and measured?
- How do epidemiological, socio-cultural, economic, and system factors influence the effectiveness of different types of contact tracing strategies?
- How are contact tracing strategies governed with respect to policy, ethics, stakeholder involvement, resource allocation (human and financial) and data protection?
Methods
This review was registered with PROSPERO (ID: CRD42023474507) and adheres to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines [26]. The search was conducted on 14/09/2023.
Eligibility criteria
Relevant descriptive and interventional studies reported in any of the six official United Nations languages, Arabic, Chinese, English, French, Russian, and Spanish, were included. No publication date restrictions were applied to the literature. Modelling studies were excluded due to uncertainties in assumptions and variability in model outputs. Contact tracing strategies for animal-to-human transmission also were excluded to focus on diseases with human-to-human transmission. Studies must have reported on contact tracing strategies or compared against another strategy. No grey literature was included.
Information sources
An electronic database search was conducted in Embase, Medline, Medline-in-process, and Cochrane libraries from database inception to September 2023. Relevant conference proceedings and additional references from experts were also considered.
Search strategy
The searches included a combination of keywords related to contact tracing and disease transmission (see S1 Table, S2 Table, S3 Table).
Selection process
Records were downloaded into a bespoke database which was used to manage citation screening. After removal of duplicate citations, titles and abstracts of the retrieved citations were screened against the predefined inclusion and exclusion criteria (see S4 Table). Studies identified as potentially relevant based on their titles or abstracts were reviewed in full and selected for inclusion according to the same criteria. Articles were screened for inclusion by two reviewers in parallel and quality checked by another reviewer. Disagreements were resolved by discussion or if no agreement was reached a third reviewer was involved in the resolution.
Data collection process
Data was extracted from all the included publications by four reviewers independently. Two additional independent reviewers conducted a quality check of the data extraction by reviewing 20% of the extractions.
Data items
In addition to publication details and study characteristics, extracted items included disease, definitions of contact persons, features of contact tracing strategy, measures and size of effect, human and technical resource requirements, and community impacts (e.g., acceptability of contact tracing, adherence to contact tracing strategies, stigma surrounding contact tracing).
Risk of bias assessment
The risk of bias assessment of randomized control trials outcomes was conducted using the revised Cochrane Risk of Bias Tool for Randomized Trials (RoB 2) [27]. The Risk Of Bias In Non-Randomized Studies - of Interventions (ROBINS-I) tool, recommended by the Cochrane Collaboration, was used for outcomes from non-randomised studies [28,29]. For qualitative studies, risk of bias was assessed using a framework based on the Critical Appraisal Skills Programme (CASP) assessment tool [30] that has been used in previous Cochrane Reviews [31–36].
Certainty assessment
The certainty of evidence for key outcomes was assessed using Grading of Recommendations Assessment, Development and Evaluation (GRADE), including Confidence in the Evidence from Reviews of Qualitative Research (CerQual) for qualitative studies [37,38].
Synthesis methods
The synthesis first involved tabulating results from included studies. Findings were then analysed descriptively across the four pre-defined focal areas relevant to public health decision making: contact tracing definitions, contact tracing effectiveness, socio-cultural aspects of contact tracing, and health systems governance of contact tracing strategies (i.e., processes, structures, and resources used to manage contact tracing) [39]. The narrative synthesis of contact tracing effectiveness focuses on non-digital contact tracing interventions as digital contact tracing interventions involve distinct methodologies and often have different primary outcomes.
Results
In total, 378 studies met the selection criteria (see Fig 1).
Study characteristics
By WHO region, 112 (29.6%) studies were from Europe, 82 (22.0%) from the Americas, 75 (19.8%) from the Western Pacific, 51 (13.5%) from Africa, 17 (4.5%) from South-East Asia, and 12 (3.2%) studies from the Eastern Mediterranean region. Most studies covered COVID-19 (n = 179; 47.4%) or tuberculosis (n = 101; 26.7%) and were retrospective (n = 91; 24.1%) or prospective (n = 79; 20.9%). There were only 12 (3.2%) randomized control trials. (see S1 Fig, S2 Fig).
Risk of bias in included studies
Most randomized control trials (n = 9; 75.%) included had either some concerns (n = 5; 41.7.%) [40–44], or high risk of bias (n = 4; 33.3.%) [45–49]. Allocation concealment was a concern in some studies [40,42,48,49], while blinding was challenging due to the nature of contact tracing methods [43,48,49]. Most non-randomised studies (n = 21; 67.7%) were at critical or serious risk of bias [50–70]. This is primarily due to missing data as the true number of contact persons is likely unknown in any contact tracing strategy, as discussed in previous reviews on contact tracing [71]. For qualitative studies, the risk of bias assessment generally showed none to very minor concerns.
The detailed risk of bias assessments for all studies assessed are in S3 Fig, S4 Fig, S5 Table, S6 Table.
Key definitions and elements of contact tracing strategies
Contact person definition.
Out of 378 included studies, 244 (64.5%) reported contact person definitions based on criteria such as physical proximity, including the duration of contact and sexual partnerships (47.6%), household exposure (27%), community exposure (14%), duration of exposure only (2%) or injection drug use (2%). Contact person definitions varied by disease type.
Most studies included used ‘close contact’ person and ‘high-risk contact’ person definitions interchangeably. However, two tuberculosis studies specifically defined high-risk contact persons with increased infection risk, such as immunocompromised individuals [72,73]. A detailed assessment is provided in S1 Box.
Contact person identification.
Contact person identification strategies were reported in 204 (54.0%) studies included. The main strategies are outlined in Table 1.
Contact person follow-up and monitoring.
A total of 168 (44.4%) studies reported on contact person follow-up strategies. Contact person follow-up strategies were categorised as either ‘active follow-up’ or ‘passive follow-up’. Active follow-up strategies included those where the contact tracer actively follows-up and interacts with the contact person, passive follow-up included strategies without interaction between a contact tracer and the contact person (see Table 2).
Active follow-up was described in 135 (35.7%) studies and included regular check-ins via phone calls or home visits (20.4%), symptom monitoring (19.0%), systematic testing (14.6%), mandatory isolation and control of its adherence (10.3%) and movement surveillance (0.3%). Passive follow-up was described in 33 (8.7%) studies and included testing referral (5.0%), recommendation for self-isolation (3.7%), treatment referral (2.4%) and contact person notification via SMS, application or email (1.3%). Some studies described several of these methods used for follow-up.
Thirteen studies (3.4%), including 11 (2.9%) on tuberculosis, one (0.3%) on leprosy and one (0.3%) on COVID-19, reported on long follow-up periods. Especially in the tuberculosis and leprosy studies, this often included several tests over many months (i.e., at 6, 12 and 24 months), to monitor for any potential reactivation or late onset of the disease [40,41,66,107,132–139].
Enabling adherence to contact tracing strategies.
Across all studies, 28 (7.4%) reported on various support mechanisms to encourage adherence to contact tracing and related measures. Main themes of incentive schemes were identified as financial incentives [7,40,63,95,99,140–149], provision of essential services [99,101,125,150–156], education and information [85,92,157], community support [158], reimbursement of costs incurred [136,144,147], and enforcement measures [61].
Among these 28 studies, only one study, Lu et al., evaluated the effectiveness of such an adherence mechanism. The randomized control trials compared a ‘high-touch contact tracing model’ (including incentives by providing social support services) with standard contact tracing, finding that the high-touch contact tracing model increased referral rates to social services by 8.4% (95% confidence interval, 0.8–15.9, p-value = 0.05) showing that social services could be effectively combined with contact tracing to reduce health inequity [156].
Effectiveness of contact tracing strategies
Among included studies, 330 (87.3%) studies examined contact tracing effectiveness across different disease areas. Previous reviews have discussed the effectiveness of contact tracing, noting that it may be effective for certain diseases in particular contexts (see S7 Table). Only one publication by the Harvard Global Health Institute presented key contact tracing performance indicators with target values (see Table 3) [159].
Mapping effectiveness measures across studies.
In the absence of other studies presenting key performance indicators with target values, effectiveness measures were mapped into performance indicators and were categorised into process, output, and impact measures following the conceptual framework of Vogt et al. (see Table 4) [68]. Most studies reported the number of contact persons identified (n = 130; 34.4%) and the contact persons screened or tested (n = 111; 29.4%) [68].
Several studies reported measures of effectiveness that related to specific diseases (i.e., quarantining for COVID-19). The following section describes the indicators that are common across multiple diseases.
Timeliness.
Timeliness of contact tracing was assessed in 48 (12.7%) studies. Most of these studies (n = 27; 7.1%) considered time to follow-up and tracing completion. The most common outcome measures included time to contact identification, time between symptom onset and start of isolation or to case investigation.
Contact person identification.
Contact person identification was assessed in 130 (34.4%) studies. The number of contact persons identified varied based on the method of contact tracing, individuals executing the tracing, as well as the types of cases and contact persons. Regarding the method of contact tracing, Hong et al. demonstrated that the contact tracing team identified more potentially exposed contact persons compared to electronic health record report (median 17 vs 9, p < .001) [160].
As for the types of contact tracers, Mulder et al. highlighted that public health nurses in the Netherlands tended to identify more contact persons than recommended in Dutch guidelines for tuberculosis contact person [161]. Similarly, specially trained midwives identified more contact persons for sexually transmissible infections (STI) in Sweden compared to contact tracers that were not specially trained [162]. Likewise, the use of nurse-led contact tracing for hepatitis B virus improved case referral rates by 14% in England [52].
Number of known contact persons among cases.
Only 16 (4.2%) studies considered the number of known contact persons among cases, which varied across studies and contexts. For example, one severe acute respiratory syndrome (SARS) contact tracing study from Canada showed that 98.7% of new cases were contact persons of the index case [163]. However, for Ebola, the proportion cases that were registered as contact persons ranged from as low as 6% in Sierra Leone [164] to 31.1% in Guinea. [165] Similarly, Richardus et al. demonstrated varying proportions of leprosy cases that were known contact persons, ranging from 90% in Bangladesh to 62% in Thailand [166].
Laxminarayan et al. reported a low number of infected contact persons traced to each index case (0.51, 95% confidence interval: 0.49-0.52) for COVID-19 [167]. Across studies, the reported proportion of cases that were known contact persons for COVID-19 ranged from 27.8% from contact tracing in the United States to 80% from contact tracing in Australia [168].
Contact persons interviewed.
Overall, 21 (5.6%) studies reported the proportion of contact persons successfully interviewed for contact tracing. Contact persons successfully interviewed ranged from 91.3% for contact tracing of high-risk COVID-19 contact persons in Belgium [169] to only 31% for COVID-19 contact tracing of the general population in the United States [112]. Reasons cited by Kanu et al. for not interviewing contact persons included: the contact person did not respond to call attempts (n = 265; 14%), had no available phone number (n = 208; 11%), refused (n = 88; 5%), was a non-resident (n = 20; 1%), or other reasons (n = 406, 22%) [112].
Cases prevented.
Two studies (0.5%) considered cases prevented via contact tracing. Duarte et al. found that when compared to targeting only close contact persons identified by case interviews, identifying contact persons from home and workplace visits prevented more tuberculosis cases (5 vs 10, respectively) in Portugal.[53] Vaughn et al. assessed contact tracing within a university within the United States and estimated that it prevented an additional 132 exposures and 22 COVID-19 infections [170].
Deaths prevented.
Four studies (1.1%) considered the association between deaths prevented and contact tracing strategies, all for diseases of airborne or direct transmission. Yalaman et al. analysed 138 countries and found that the implementation of comprehensive national contact tracing policies (i.e., contact tracing for each identified case) was significantly associated with a reduction in COVID-19 case fatality (β = −0.13, p < 0.05) [171]. Similarly, in Colombia, Fernández-Niño et al. found that tracing of at least five contact persons per COVID-19 case reduces fatality by 48% (95% confidence interval [45,51]). [172] Kanu et al. assessed the impact of contact tracing combined with state-mandated stay-at-home orders, public mask mandates, and case investigation in the United States. They determined that this strategy led to an 100% reduction in COVID-19 mortality [112].
Martinson et al. examined the risk of death among contact persons that developed tuberculosis comparing home tracing and intensive HIV/ tuberculosis screening or standard of care (clinic referral letters) in South Africa. The deaths in both groups were comparable (1.0% vs 1.2%) [41].
Incidence reduction.
Only one (0.3%) study assessed incidence reduction. Kanu et al. found that contact tracing led to an 82% reduction in COVID-19 incidence when combined with state-mandated stay-at-home orders, public mask mandates, and case investigation [112].
Effectiveness by contact tracing modality.
Seventeen (4.5%) studies assessed the comparative effectiveness of different modalities with varied results (see S8 Table). Memory retrieval techniques during interviews and specialised contact tracers helped identify more contact persons compared to not using these modalities [46,52,162]. Different testing mechanisms influenced the outcomes, such as combining serological rapid diagnostic testing with reverse transcriptase polymerase chain reaction (RT-PCR) leading to a reduction in the number of contact persons needing to quarantine [76]. Involving community health workers increased rates of contact tracing completion [64].
Socio-cultural factors affecting the effectiveness of contact tracing
Among included studies, 166 (43.9%) studies examined socio-cultural factors that affect contact tracing. Challenges in contact person follow-up have been reported as resistance from the public to quarantining [173]. Certain groups, such as healthcare workers, children, and individuals with high transmission potential, received special attention in some studies, indicating a targeted approach to contact tracing and management [73,103,133,173–178].
Across all studies, 26 (6.9%) reported on various support mechanisms to encourage adherence to contact tracing and related measures. Main themes included financial incentives, provision of essential services, education and information, enforcement measures, community support, and reimbursement for costs. Finally, 14 (3.7%) studies reported that privacy and data security emerged as significant concerns, with attention to protecting patient confidentiality and maintaining safeguards [104,125,179,180]. The perceived intrusiveness of programs, such as active surveillance and movement restrictions, raised concerns about autonomy in certain contexts [133,181,182].
Health systems governance of contact tracing strategies
Implementation.
The review identified 278 (73.5%) studies that examined health systems governance of contact tracing. Contact tracing often involves multiple actors across different levels including international bodies, national governments, provincial authorities, and local health professionals or volunteers (see S5 Fig).
Across studies, 207 (54.8%) reported the level of implementation. Strategies were implemented locally in 97 (25.7%) studies, nationally in 69 (18.3%) studies, and regionally in 41 (10.9%) studies. Strategies described in five (1.3%) studies spanned across countries, typically for air-travel (n = 3), reflecting coordinated efforts and a global approach [80,153,183–185].
Strategies often aligned with wider health policies or responded to specific health crises (e.g., COVID-19, Ebola, SARS). For example, Amisi et al. described child tuberculosis contact management within the context of Kenya’s efforts to manage their high rate of tuberculosis [186].
In 17 (4.5%) studies, contact tracing efforts influenced public health interventions. For instance, the findings of a local and domestic Ebola contact tracing strategy prompted the US Centers for Disease Control and Prevention to revise its guidelines on movement and Ebola monitoring [101]. Similarly, a regional tuberculosis strategy resulted in the National Health Security Office of Thailand agreeing to fund tuberculosis screening for household contact persons, irrespective of symptoms [141].
Human resources.
In total, 186 (49.2%) studies described the human resources of contact tracing strategies. Strategies often involved multidisciplinary teams, including healthcare staff (physicians, nurses, health workers), public health officials, epidemiologists, field investigators, disease intervention specialists, and community volunteers [99,118,122,125,141,152,153,176,180,187–191].
Several studies emphasised targeted training and ongoing capacity building for effective contact tracing [122,125,152,153,176,187]. Some studies involved such programs to prepare healthcare workers, community health volunteers, and deploy field staff with the necessary skills to effectively carry out contact tracing procedures [99,118,141,153,188]. Four studies noted that the lack of coordination between local management and volunteers, as well as the non-response rate created a substantial workload for volunteers and staff, needing substantial human resources [180,189–191].
Moreover, some studies noted that the resource-intensive nature of contact tracing demanded significant workforce involvement. They required substantial involvement and management from clinical and administrative staff to ensure the quality of the workforce [190]. Studies demonstrated that contact tracing can be emotionally demanding for contact tracers, especially during public health crises [64,133,192,193]. In one study, healthcare workers valued the extra support that stakeholders provided in the implementation of contact tracing to reduce the time and burden on staff [133]. One study from the USA specified a benchmark of 30 tracers per 100,000 population for COVID-19 case investigation and contact tracing [194].
Collaboration across entities, including public health departments and other government agencies, private software developers, academic institutions, and community-based organisations, and non-governmental organisations was a recurring theme.12,18–22 Studies suggested that well-trained, cross-functional teams could be efficient in conducting interviews, administering tests, and managing contact tracing processes. Additionally, certain roles, like epidemiologists, data managers, and administrative staff, require specialised skills to ensure effective contact tracing and data management [111,195–197]. Common challenges discussed among studies included staff shortages, workload issues, limited resources (such as delays in testing samples and equipment), and the need for additional support from non-governmental organisations or private practitioners [122,198–200].
Finally, 22 (5.8%) studies noted the use of community health workers and leaders. These studies found that community members had a good understanding of the local context and would be able to provide local insights, including cultural nuances, social dynamics, and community structures [64,70,77,80,96,200]. Studies reported that community engagement built trust, facilitated information exchange, and promoted a more targeted and culturally sensitive approach to contact tracing [59,152]. Cultural competence and language skills were also mentioned to establish rapport with individuals and improve the likelihood of cooperation within communities, especially in studies that focused more on community-based contact tracing [98,194,199]. Research suggested that contact tracers should convey information clearly and gather information from cases on contact persons as well as provide guidance in a supportive manner [118,199,201].
Technical resources.
In total, 94 (24.9%) studies included digital methods of contact tracing. Bluetooth and Global Positioning System (GPS) (in COVID-19, Ebola and Mpox studies) technologies were used for proximity tracking [146,202], sometimes this was linked with decentralised data storage for privacy.8 Geolocation software utilised GPS (in COVID-19, Ebola, tuberculosis and Pertussis studies) and Closed-Circuit Television (CCTV) data (in COVID-19, Middle East respiratory syndrome (MERS) and Mpox studies) [55,203,204]. Mobile applications (in COVID-19, tuberculosis, Ebola, Chlamydia studies) and exposure notification networks (in COVID-19, tuberculosis and Chlamydia studies) were useful for linking contact persons with cases through exchanging data among users [205]. Cloud-based systems ensured secure data transfer in the majority of studies describing digital methods supporting contact tracing (in COVID-19, Mpox, tuberculosis, Hepatitis B, Ebola studies) [145,152,206]. Data processing algorithms, such as Cross-Industry Standard Process (CRISP) were also used to enhance data collection and analysis (in COVID-19, tuberculosis and Mpox studies)[196]. Sometimes, credit card transaction logs (in COVID-19 and Mpox studies) were used [89]. Additionally, one Syphilis study reported using Facebook to identify contact persons [207].
Elements of manual methods, involving human contact tracers, contact person cards, and home visit workbooks were reported in most included studies (253, 66.9%) studies [166,208–210]. For example some strategies provided invitation cards to index cases to invite their contact persons to participate [54,141,211].
Health information systems like the Calendaring and Scheduling Consortium (CalCONNECT) [156] and District Health Information Software 2 (DHIS2) [212] integrated data platforms were also utilised, involving national health management data platforms for efficient data entry and analysis. Notification systems consisted of automated messaging, and emergency management software for effective communication (in COVID-19 studies) [92,190].
Financial resources.
Contact tracing has many financial implications including renumeration, testing and diagnostics, and incentives. Compensation for individuals involved in the contact tracing process includes personnel wages and travel costs associated with commuting to and from their place of employment as well as the cost involved in physically moving around to trace contact [101,141,144]. One (0.3%) study mentioned that delays in payments for tracers decreased their motivation to work [96]. A cost associated with testing and diagnostic equipment such as X-ray machines, as well as laboratory technicians and other individuals who may be involved with testing and diagnostics was reported [63,72]. In some contact tracing strategies, index patients were offered a financial incentive for every contact person they identified, and contact persons were financially compensated if they presented themselves for testing [142,143].
Funding mechanisms were varied and included government funding [213], specific government programs [156,194], non-governmental organisations [133,200], private sector contributions [200], religious institutions [214], individual donors [214], and public health organisations such as the WHO [189].
The cost per case detected was only reported in four (1.1%) studies. Costs ranged from $33 for COVID-19 to $2,200 for HIV. The considerable variability in the data may be attributable to significant differences among the four studies regarding disease focus, the range of costs incorporated in the estimations, country settings, and the time periods analysed.
Discussion
To our knowledge, this is the first global systematic review to look at contact tracing across all infectious diseases with human-to-human transmission. The review included 378 studies, and examined the definitions, effectiveness, socio-cultural aspects, and health systems governance of contact tracing strategies. Most studies originated from Europe and North America and focused on diseases such as COVID-19 and tuberculosis.
The effectiveness of contact tracing is influenced by several key factors. Effective health systems governance and adherence to established standards and norms are essential for the successful implementation of contact tracing strategies. Adherence by the affected population is critical, with trust playing a significant role [7,215–217]. In line with previous research, this review also highlights that reinforcing community connections through engaging local non-governmental organisations and community leaders can strengthen contact tracing efforts [218]. Additionally, integrating contact tracing with broader public health and social measures may enhance adherence [101,141].
These factors are influenced by the context and disease characteristics, with variability in success rates across different diseases and settings. Disease-specific indicators, such as reinfection rates for STIs, vaccination for hepatitis B, and quarantine measures for COVID-19, were commonly reported. The data identified could be used in the development of contact tracing strategies or guidelines for novel or emerging infectious diseases.
The paucity of evidence regarding output, outcome, and impact indicators for contact tracing effectiveness is a notable finding. This gap constrains our understanding of contact tracing’s efficacy in different epidemic contexts. Addressing this issue is crucial for optimising contact tracing strategies and improving epidemic preparedness. To address this gap, we recommend that researchers and program managers implementing contact tracing interventions should prepare monitoring and evaluation plans that define and enable measurement of input, process, output, outcome, and impact indicators where feasible, as proposed in a scoping review of contact tracing for COVID-19 [219]. In particular, output (e.g., case isolation, contact quarantine) and outcome (transmission reduction) indicators should be prioritised in addition to process indicators that are currently more commonly measured, to enable effectiveness evaluations for contact tracing for different infectious diseases.
In addition to effectiveness, acceptability of contact tracing strategies varied significantly by country and infection type, influenced by factors like stigma and privacy concerns [10–13,100]. These structures were central for enhancing operational efficiency and ensuring the resilience of the contact tracing workforce. However, the review of the literature has shown that the effectiveness of the process is determined by several factors, including the disease characteristics, as well as the social, cultural, economic, and political context where the pathogen is identified and may spread.
Equitable access and community engagement are pivotal, necessitating proactive measures to address disparities and ensure inclusive participation [60,152]. The evolving landscape of digital tools holds transformative potential for contact tracing but requires continuous technological advancements and strict privacy adherence. Although, the effectiveness of digital strategies was beyond the scope of this review.
Our review indicated that contact tracing demands thorough workforce management and significant resources. A recent study by Islam et al. highlights similar issues, emphasising the need for contextualised guidance, effective implementation strategies, and comprehensive training to enhance the effectiveness of contact tracing efforts [220]. The study underlines the importance of tailored guidance and ongoing education to address local, social, cultural, and infrastructural nuances and improve the overall impact of contact tracing initiatives, in line with current research and the evidence identified through our review [122,125,152,153,176,187,220,221].
Similarly, collaboration emerged as a key element in contact tracing strategies identified through the review. However, challenges like staff shortages and resource constraints persist. Effective training and robust mental health support for contact tracers are fundamental for sustaining workforce resilience and have been demonstrated as improving contact tracing effectiveness across various contexts [99,118,122,125,141,152,153,176,180,187–191]. Sustained financial investment is required to support the resource-intensive nature of contact tracing. Efficient allocation of resources and prioritisation of contact tracing efforts based on cost-benefit analyses can further enhance effectiveness [133,156,189,194,200,213,214].
Limitations
This review highlights several limitations. Within the literature base, the predominance of studies from Europe and North America limits generalisability. Moreover, most studies focused on COVID-19 (n = 179; 47.4%) followed by tuberculosis (n = 101; 26.7%). All other diseases were the focus of only 2–12 studies each. The urgency and global impact of the COVID-19 pandemic might have influenced the design, execution, and outcomes of contact tracing strategies, which could limit the applicability of our findings to other epidemics and pathogens with different modes of transmission and epidemiological characteristics. The reliance on descriptive or non-randomised studies underscores the need for more rigorous and comparable operational research methodologies. The number of actual trials included in this review is relatively small compared to the total number of studies. This could potentially limit the robustness of our findings and conclusions, as trials often provide more definitive evidence compared to other types of studies. Additionally, the review does not comprehensively address how factors like outbreak dynamics and disease characteristics impact contact tracing effectiveness in curbing the attack rate and cost-effectiveness of the intervention. Furthermore, the effectiveness of digital contact tracing tools was not explored in depth. Lastly, in the identified evidence for effectiveness of contact tracing strategies, no analysis was conducted to assess the quality of the identified contact persons, including assessments of whether any of them were infected.
Future research needs
Future research should aim to establish standardised metrics for comparative analysis, explore the impact of contact tracing strategies on disease incidence and mortality, and expand research beyond Europe and North America, and beyond diseases like COVID-19 and tuberculosis. There is a need to optimise community-based approaches to account for local nuances and cultural sensitivities. Evaluating the interplay between health systems governance models, resource allocation, workforce support, and overall effectiveness is essential. Additionally, future research should investigate the long-term effects of integrating contact tracing with broader health policies.
By addressing these gaps, future research can enhance the understanding and implementation of effective contact tracing strategies for novel and emerging infectious diseases.
Supporting information
S1 Table. Search terms for EMBASE and MEDLINE via Embase.com (Elsevier; https://www.embase.com).
https://doi.org/10.1371/journal.pgph.0004579.s001
(DOCX)
S2 Table. Search terms for MEDLINE and MEDLINE IN-PROCESS via PubMed (NIH National Library of Medicine, https://pubmed.ncbi.nlm.nih.gov/).
https://doi.org/10.1371/journal.pgph.0004579.s002
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S3 Table. Search terms for the Cochrane Methodology Register and Cochrane Database of Systematic Reviews (via the Cochrane Library, https://www.cochranelibrary.com/advanced-search/search-manager).
https://doi.org/10.1371/journal.pgph.0004579.s003
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S5 Table. Risk of bias in included qualitative studies.
https://doi.org/10.1371/journal.pgph.0004579.s005
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S6 Table. GRADE CerQual Evidence Profile for qualitative studies.
https://doi.org/10.1371/journal.pgph.0004579.s006
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S8 Table. Comparative effectiveness of contact tracing strategies.
https://doi.org/10.1371/journal.pgph.0004579.s008
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S1 Fig. Disease areas across included studies.
Note: Some studies considered more than one disease. “Other single disease” includes methicillin-resistant Staphylococcus aureus (MRSA) infection, mumps, pertussis, severe acute respiratory syndrome (SARS), scarlet fever, (n = 1 for each).
https://doi.org/10.1371/journal.pgph.0004579.s009
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S3 Fig. Risk of bias in included randomized control trials.
https://doi.org/10.1371/journal.pgph.0004579.s011
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S4 Fig. Risk of bias in included non-randomized studies.
https://doi.org/10.1371/journal.pgph.0004579.s012
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S5 Fig. Example of governance strategy for COVID-19.
https://doi.org/10.1371/journal.pgph.0004579.s013
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S1 Data. WHO contact tracing list of studies: includes all 9935 articles that were found through the search strategy.
https://doi.org/10.1371/journal.pgph.0004579.s015
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S2 Data. Data Extraction Template_final_v3.0: includes data from the 378 studies that were retained for the review.
https://doi.org/10.1371/journal.pgph.0004579.s016
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Acknowledgments
The authors acknowledge Nikunj Dobariya, Lara Gerhardt, Eddy Lang, Jingya Li, Atara Loar, and Médy Sleiman for their invaluable contributions in research assistance and medical writing support for the systematic literature review.
References
- 1. Hossain AD, Jarolimova J, Elnaiem A, Huang CX, Richterman A, Ivers LC. Effectiveness of contact tracing in the control of infectious diseases: a systematic review. Lancet Public Health. 2022;7(3):e259–73. pmid:35180434
- 2. Brandt AM. The history of contact tracing and the future of public health. Am J Public Health. 2022;112(8):1097–9. pmid:35830671
- 3. Nakayama DK. Social distancing and contact tracing during the great plague of 1665. Am Surg. 2022;88(2):165–6. pmid:34974710
- 4. Müller J, Kretzschmar M. Contact tracing - Old models and new challenges. Infect Dis Model. 2020;6:222–31. pmid:33506153
- 5. World Health Organization. Coronavirus disease (COVID-19): Contact tracing. Available from: https://www.who.int/news-room/questions-and-answers/item/coronavirus-disease-covid-19-contact-tracing
- 6. Juneau C-E, Briand A-S, Collazzo P, Siebert U, Pueyo T. Effective contact tracing for COVID-19: a systematic review. Glob Epidemiol. 2023;5:100103. pmid:36959868
- 7. Garrett PM, White JP, Lewandowsky S, Kashima Y, Perfors A, Little DR, et al. The acceptability and uptake of smartphone tracking for COVID-19 in Australia. PLoS One. 2021;16(1):e0244827. pmid:33481841
- 8. Osmanlliu E, Paquette J, Rodriguez Duarte MA, Bédard S, de Marcellis-Warin N, Zhegu M, et al. Public perspectives on exposure notification apps: a patient and citizen co-designed study. J Pers Med. 2022;12(5):729. pmid:35629150
- 9. Fields VL, Kiphibane T, Eason JT, Hafoka SF, Lopez AS, Schwartz A, et al. Assessment of contact tracing for COVID-19 among people experiencing homelessness, Salt Lake County Health Department, March-May 2020. Ann Epidemiol. 2021;59:50–5. pmid:33894384
- 10. Hogan K, Macedo B, Macha V, Barman A, Jiang X. Contact tracing apps: lessons learned on privacy, autonomy, and the need for detailed and thoughtful implementation. JMIR Med Inform. 2021;9(7):e27449. pmid:34254937
- 11. Sowmiya B, Abhijith VS, Sudersan S, Sakthi Jaya Sundar R, Thangavel M, Varalakshmi P. A survey on security and privacy issues in contact tracing application of COVID-19. SN Computer Science. 2021;2:1–11.
- 12. Saeed F, Mihan R, Mousavi SZ, Reniers RL, Bateni FS, Alikhani R, et al. A narrative review of stigma related to infectious disease outbreaks: what can be learned in the face of the covid-19 pandemic?. Front Psychiatry. 2020;11:565919. pmid:33343414
- 13. Mouliou DS, Gourgoulianis KI. False-positive and false-negative COVID-19 cases: respiratory prevention and management strategies, vaccination, and further perspectives. Expert Rev Respir Med. 2021;15(8):993–1002. pmid:33896332
- 14. Mathevet I, Ost K, Traverson L, Zinszer K, Ridde V. Accounting for health inequities in the design of contact tracing interventions: a rapid review. Int J Infect Dis. 2021;106:65–70. pmid:33716194
- 15. Pozo-Martin F, Beltran Sanchez MA, Müller SA, Diaconu V, Weil K, El Bcheraoui C. Comparative effectiveness of contact tracing interventions in the context of the COVID-19 pandemic: a systematic review. Eur J Epidemiol. 2023; 243–266.
- 16. Rafferty AC, Bofkin K, Hughes W, Souter S, Hosegood I, Hall RN, et al. Does 2x2 airplane passenger contact tracing for infectious respiratory pathogens work? A systematic review of the evidence. PLoS One. 2023;18(2):e0264294. pmid:36730309
- 17. Ayouni I, Maatoug J, Dhouib W, Zammit N, Fredj SB, Ghammam R, et al. Effective public health measures to mitigate the spread of COVID-19: a systematic review. BMC Public Health. 2021;21(1):1015. pmid:34051769
- 18. Jenniskens K, Bootsma MCJ, Damen JAAG, Oerbekke MS, Vernooij RWM, Spijker R, et al. Effectiveness of contact tracing apps for SARS-CoV-2: a rapid systematic review. BMJ Open. 2021;11(7):e050519. pmid:34253676
- 19. Littlecott H, Herd C, O’Rourke J, Chaparro LT, Keeling M, James Rubin G, et al. Effectiveness of testing, contact tracing and isolation interventions among the general population on reducing transmission of SARS-CoV-2: a systematic review. Philos Trans A Math Phys Eng Sci. 2023;381(2257):20230131. pmid:37611628
- 20. Mbivnjo EL, Lynch M, Huws JC. Measles outbreak investigation process in low- and middle-income countries: a systematic review of the methods and costs of contact tracing. Z Gesundh Wiss. 2022;30(10):2407–26. pmid:34026422
- 21. Sagili KD, Muniyandi M, Shringarpure K, Singh K, Kirubakaran R, Rao R, et al. Strategies to detect and manage latent tuberculosis infection among household contacts of pulmonary TB patients in high TB burden countries - a systematic review and meta-analysis. Trop Med Int Health. 2022;27(10):842–63. pmid:35927930
- 22. Bannister-Tyrrell M, Chen M, Choi V, Miglietta A, Galea G. Systematic scoping review of the implementation, adoption, use, and effectiveness of digital contact tracing interventions for COVID-19 in the Western Pacific Region. Lancet Reg Health West Pac. 2023;34:100647. pmid:37256207
- 23. Velen K, Shingde RV, Ho J, Fox GJ. The effectiveness of contact investigation among contacts of tuberculosis patients: a systematic review and meta-analysis. Eur Respir J. 2021;58(6):2100266. pmid:34016621
- 24. 24.World Health Organization. Online global consultation on contact tracing for COVID-19. 9-11 June 2020. 2021 [cited 8 Sep 2023. ]. Available from: https://www.who.int/publications/i/item/online-global-consultation-on-contact-tracing-for-covid-19-9-11-june-2020
- 25.
World Health Organization. WHO guideline on contact tracing. World Health Organization; 2024. Available from: https://iris.who.int/handle/10665/380060.
- 26. Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. Syst Rev. 2021;10(1):89. pmid:33781348
- 27. Sterne JA, Savović J, Page MJ, Elbers RG, Blencowe NS, Boutron I, et al . RoB 2: a revised tool for assessing risk of bias in randomised trials. BMJ. 2019;366.
- 28. Sterne JA, Hernán MA, McAleenan A, Reeves BC, Higgins JP. Assessing risk of bias in a non‐randomized study. Cochrane Handbook for Systematic Reviews of Interventions. 2019;621–641.
- 29. Shea BJ, Reeves BC, Wells G, Thuku M, Hamel C, Moran J, et al. AMSTAR 2: a critical appraisal tool for systematic reviews that include randomised or non-randomised studies of healthcare interventions, or both. BMJ. 2017;358:j4008. pmid:28935701
- 30. Critical Appraisal Skills Programme C. CASP Qualitative Studies Checklist. Available from: https://casp-uk.net/casp-tools-checklists/
- 31. Glenton C, Carlsen B, Lewin S, Wennekes MD, Winje BA, Eilers R, et al. Healthcare workers’ perceptions and experiences of communicating with people over 50 years of age about vaccination: a qualitative evidence synthesis. Cochrane Database Syst Rev. 2021;7(7):CD013706. pmid:34282603
- 32. Ames HM, Glenton C, Lewin S, Tamrat T, Akama E, Leon N. Clients’ perceptions and experiences of targeted digital communication accessible via mobile devices for reproductive, maternal, newborn, child, and adolescent health: a qualitative evidence synthesis. Cochrane Database Syst Rev. 2019;10(10):CD013447. pmid:31608981
- 33. Ames HM, Glenton C, Lewin S. Parents’ and informal caregivers’ views and experiences of communication about routine childhood vaccination: a synthesis of qualitative evidence. Cochrane Database Syst Rev. 2017;2(2):CD011787. pmid:28169420
- 34. Houghton C, Meskell P, Delaney H, Smalle M, Glenton C, Booth A, et al. Barriers and facilitators to healthcare workers’ adherence with infection prevention and control (IPC) guidelines for respiratory infectious diseases: a rapid qualitative evidence synthesis. Cochrane Database Syst Rev. 2020;4(4):CD013582. pmid:32315451
- 35. Karimi-Shahanjarini A, Shakibazadeh E, Rashidian A, Hajimiri K, Glenton C, Noyes J, et al. Barriers and facilitators to the implementation of doctor-nurse substitution strategies in primary care: a qualitative evidence synthesis. Cochrane Database Syst Rev. 2019;4(4):CD010412. pmid:30982950
- 36. Munabi-Babigumira S, Glenton C, Lewin S, Fretheim A, Nabudere H. Factors that influence the provision of intrapartum and postnatal care by skilled birth attendants in low- and middle-income countries: a qualitative evidence synthesis. Cochrane Database Syst Rev. 2017;11(11):CD011558. pmid:29148566
- 37.
Ryan R, Hill S. How to GRADE the quality of the evidence. Cochrane Consumers and Communication Group; 2016. Available from: http://cccrg.cochrane.org/author-resources
- 38. Lewin S, Booth A, Glenton C, Munthe-Kaas H, Rashidian A, Wainwright M, et al. Applying GRADE-CERQual to qualitative evidence synthesis findings: introduction to the series. Implement Sci. 2018;13(Suppl 1):2. pmid:29384079
- 39. Health Systems Governance. [cited 17 Dec 2024. ]. Available from: https://www.who.int/health-topics/health-systems-governance
- 40. Fox GJ, Nhung NV, Sy DN, Hoa NLP, Anh LTN, Anh NT, et al. Household-Contact Investigation for Detection of Tuberculosis in Vietnam. N Engl J Med. 2018;378(3):221–9. pmid:29342390
- 41. Martinson NA, Lebina L, Webb EL, Ratsela A, Varavia E, Kinghorn A, et al. Household Contact Tracing With Intensified Tuberculosis and Human Immunodeficiency Virus Screening in South Africa: A Cluster-Randomized Trial. Clin Infect Dis. 2022;75(5):849–56. pmid:34950944
- 42. Ayles H, Muyoyeta M, Du Toit E, Schaap A, Floyd S, Simwinga M, et al. Effect of household and community interventions on the burden of tuberculosis in southern Africa: the ZAMSTAR community-randomised trial. Lancet. 2013;382(9899):1183–94. pmid:23915882
- 43. Raymond C, Ouyang D, D’Agostino A, Rudman SL, Ho DE. Automated vs. manual case investigation and contact tracing for pandemic surveillance: Evidence from a stepped wedge cluster randomized trial. EClinicalMedicine. 2022;55:101726. pmid:36386031
- 44. Sharif MA, Dixon E, Bair EF, Garzon C, Gibson L, Linn K, et al. Effect of Nudges on Downloads of COVID-19 Exposure Notification Apps: A Randomized Clinical Trial. JAMA Netw Open. 2021;4(12):e2140839. pmid:34940870
- 45. Clark JL, Segura ER, Oldenburg CE, Salvatierra HJ, Rios J, Perez-Brumer AG, et al. Traditional and Web-Based Technologies to Improve Partner Notification Following Syphilis Diagnosis Among Men Who Have Sex With Men in Lima, Peru: Pilot Randomized Controlled Trial. J Med Internet Res. 2018;20(7):e232. pmid:29970355
- 46. Evans JR, Dawson HR, Chae H, Goldfarb D, Fisher RP, Dianiska RE, et al. Enhancing the effectiveness of contact tracing interviews: A randomized controlled experiment of an enhanced cognitive interview protocol. Am J Infect Control. 2022;50(6):631–7. pmid:34971713
- 47. Davis JL, Turimumahoro P, Meyer AJ, Ayakaka I, Ochom E, Ggita J, et al. Home-based tuberculosis contact investigation in Uganda: a household randomised trial. ERJ Open Res. 2019;5(3):00112–2019. pmid:31367636
- 48. Salazar-Austin N, Cohn S, Barnes GL, Tladi M, Motlhaoleng K, Swanepoel C, et al. Improving Tuberculosis Preventive Therapy Uptake: A Cluster-randomized Trial of Symptom-based Versus Tuberculin Skin Test-based Screening of Household Tuberculosis Contacts Less Than 5 Years of Age. Clin Infect Dis. 2020;70(8):1725–32. pmid:31127284
- 49. Toomey KE, Peterman TA, Dicker LW, Zaidi AA, Wroten JE, Carolina J. Human immunodeficiency virus partner notification. Cost and effectiveness data from an attempted randomized controlled trial. Sex Transm Dis. 1998;25(6):310–6. pmid:9662766
- 50. Ansari S, Thomas S, Campbell IA, Furness L, Evans MR. Refined tuberculosis contact tracing in a low incidence area. Respir Med. 1998;92(9):1127–31. pmid:9926167
- 51. Aung AH, Li AL, Kyaw WM, Khanna R, Lim W-Y, Ang H, et al. Harnessing a real-time location system for contact tracing in a busy emergency department. J Hosp Infect. 2023;141:63–70. pmid:37660888
- 52. Beebeejaun K, Amin-Chowdhury Z, Letley L, Kara E, Mahange B, Harrington K, et al. Impact of a nurse-led enhanced monitoring, management and contact tracing intervention for chronic hepatitis B in England, 2015-2017. J Viral Hepat. 2021;28(1):72–9. pmid:32926589
- 53. Duarte R, Neto M, Carvalho A, Barros H. Improving tuberculosis contact tracing: the role of evaluations in the home and workplace. Int J Tuberc Lung Dis. 2012;16(1):55–9. pmid:22236846
- 54. Edmiston N, Merritt T, Ooi C. Make contact: a comparative study of contact tracing strategies. Int J STD AIDS. 2010;21(6):431–4. pmid:20606225
- 55. Geenen C, Raymenants J, Gorissen S, Thibaut J, McVernon J, Lorent N, et al. Individual level analysis of digital proximity tracing for COVID-19 in Belgium highlights major bottlenecks. medRxiv. 2023.
- 56. Ha YP, Tesfalul MA, Littman-Quinn R, Antwi C, Green RS, Mapila TO, et al. Evaluation of a mobile health approach to tuberculosis contact tracing in botswana. J Health Commun. 2016;21(10):1115–21. pmid:27668973
- 57. Hellmich TR, Clements CM, El-Sherif N, Pasupathy KS, Nestler DM, Boggust A, et al. Contact tracing with a real-time location system: a case study of increasing relative effectiveness in an emergency department. Am J Infect Control. 2017;45(12):1308–11. pmid:28967513
- 58. Ho HJ, Zhang ZX, Huang Z, Aung AH, Lim W-Y, Chow A. Use of a real-time locating system for contact tracing of health care workers during the COVID-19 pandemic at an infectious disease center in singapore: validation study. J Med Internet Res. 2020;22(5):e19437. pmid:32412416
- 59. Kenu E, Barradas DT, Bandoh DA, Frimpong JA, Noora CL, Bekoe FA. Community-Based Surveillance and Geographic Information System‒Linked Contact Tracing in COVID-19 Case Identification, Ghana, March‒June 2020. Emerg Infect Dis. 2022;28(13):S114–20. pmid:36502391
- 60. King D, Chown R, Clarke J. Forty years on--contact tracing in Wakefield. Int J STD AIDS. 1996;7(5):362–4. pmid:8894827
- 61. Leung KK, Zhang R, Hashim MJ, Fang M, Xu J, Sun D, et al. Effectiveness of containment strategies in preventing SARS-CoV-2 transmission. J Infect Public Health. 2022;15(6):609–14. pmid:35537237
- 62. Malheiro R, Figueiredo AL, Magalhães JP, Teixeira P, Moita I, Moutinho MC, et al. Effectiveness of contact tracing and quarantine on reducing COVID-19 transmission: a retrospective cohort study. Public Health. 2020;189:54–9. pmid:33160088
- 63. Myint O, Sriplung H, San CC, Chongsuvivatwong V. Additional active tuberculosis cases detected and costs incurred by a second household contact investigation. Public Health Action. 2019;9(4):182–5. pmid:32042613
- 64. Ospina JE, Orcau A, Millet J-P, Sánchez F, Casals M, Caylà JA. Community health workers improve contact tracing among immigrants with tuberculosis in Barcelona. BMC Public Health. 2012;12:158. pmid:22394990
- 65. Raymenants J, Geenen C, Thibaut J, Nelissen K, Gorissen S, Andre E. Empirical evidence on the efficiency of backward contact tracing in COVID-19. Nat Commun. 2022;13(1):4750. pmid:35963872
- 66. Rekha B, Jagarajamma K, Chandrasekaran V, Wares F, Sivanandham R, Swaminathan S. Improving screening and chemoprophylaxis among child contacts in India’s RNTCP: a pilot study. Int J Tuberc Lung Dis. 2013;17(2):163–8. pmid:23317950
- 67. Ritsema F, Bosdriesz JR, Leenstra T, Petrignani MWF, Coyer L, Schreijer AJM, et al. Factors Associated With Using the COVID-19 Mobile Contact-Tracing App Among Individuals Diagnosed With SARS-CoV-2 in Amsterdam, the Netherlands: Observational Study. JMIR Mhealth Uhealth. 2022;10(8):e31099. pmid:35867842
- 68. Vogt F, Haire B, Selvey L, Katelaris AL, Kaldor J. Effectiveness evaluation of digital contact tracing for COVID-19 in New South Wales, Australia. Lancet Public Health. 2022;7(3):e250–8. pmid:35131045
- 69. Weaver SC, Byrne SS, Bruce H, Vargas OL, Robey TE. Prospective Case-control Study of Contact Tracing Speed for Emergency Department-based Contact Tracers. West J Emerg Med. 2022;23(5):623–7. pmid:36205662
- 70. Eang MT, Satha P, Yadav RP, Morishita F, Nishikiori N, van-Maaren P, et al. Early detection of tuberculosis through community-based active case finding in Cambodia. BMC Public Health. 2012;12:469. pmid:22720878
- 71. Anglemyer A, Moore TH, Parker L, Chambers T, Grady A, Chiu K, et al. Digital contact tracing technologies in epidemics: a rapid review. Cochrane Database Syst Rev. 2020;8(8):CD013699. pmid:33502000
- 72. Bagdasarian N, Chan HC, Ang S, Isa MS, Chan SM, Fisher DA. A “Stone in the Pond” Approach to Contact Tracing: Responding to a Large-Scale, Nosocomial Tuberculosis Exposure in a Moderate TB-Burden Setting. Infect Control Hosp Epidemiol. 2017;38(12):1509–11. pmid:29179783
- 73. Park SY, Lee EJ, Kim YK, Lee SY, Kim GE, Jeong YS, et al. Aggressive contact investigation of in-hospital exposure to active pulmonary tuberculosis. J Korean Med Sci. 2019;34(7):e58. pmid:30804729
- 74. Skrip LA, Fallah MP, Gaffney SG, Yaari R, Yamin D, Huppert A, et al. Characterizing risk of Ebola transmission based on frequency and type of case-contact exposures. Philos Trans R Soc Lond B Biol Sci. 2017;372(1721):20160301. pmid:28396472
- 75. Buchholz U, Müller MA, Nitsche A, Sanewski A, Wevering N, Bauer-Balci T, et al. Contact investigation of a case of human novel coronavirus infection treated in a German hospital, October-November 2012. Euro Surveill. 2013;18(8):20406. pmid:23449231
- 76. Charbonnier L, Rouprêt-Serzec J, Caseris M, Danse M, Cointe A, Cohen L, et al. Contribution of serological rapid diagnostic tests to the strategy of contact tracing in households following SARS-CoV-2 infection diagnosis in children. Front Pediatr. 2021;9:638502. pmid:34041206
- 77. Nachega JB, Atteh R, Ihekweazu C, Sam-Agudu NA, Adejumo P, Nsanzimana S, et al. Contact tracing and the COVID-19 response in Africa: best practices, key challenges, and lessons learned from Nigeria, Rwanda, South Africa, and Uganda. Am J Trop Med Hyg. 2021;104(4):1179–87. pmid:33571138
- 78. Nachega JB, Grimwood A, Mahomed H, Fatti G, Preiser W, Kallay O, et al. From easing lockdowns to scaling up community-based coronavirus disease 2019 screening, testing, and contact tracing in africa-shared approaches, innovations, and challenges to minimize morbidity and mortality. Clin Infect Dis. 2021;72(2):327–31. pmid:33501963
- 79. Verdonck K, Morreel S, Vanhamel J, Vuylsteke B, Nöstlinger C, Laga M, et al. Local initiative supports case isolation and contact tracing during a SARS-CoV-2 surge in summer 2020: a community case study in Antwerp, Belgium. Front Public Health. 2023;11:1000617. pmid:37213599
- 80. Koura KG, Mbitikon OB, Fiogbé AA, Ouédraogo AR, Kuate Kuate A, Magassouba AS, et al. Programmatic implementation of contact investigation in Eight African Countries. Trop Med Infect Dis. 2022;8(1):29. pmid:36668936
- 81. Puryear S, Seropola G, Ho-Foster A, Arscott-Mills T, Mazhani L, Firth J, et al. Yield of contact tracing from pediatric tuberculosis index cases in Gaborone, Botswana. Int J Tuberc Lung Dis. 2013;17(8):1049–55. pmid:23827029
- 82. Grande D, Mitra N, Marti XL, Merchant R, Asch D, Dolan A, et al. Consumer views on using digital data for COVID-19 Control in the United States. JAMA Netw Open. 2021;4(5):e2110918. pmid:34009347
- 83. Zimmermann BM, Fiske A, Prainsack B, Hangel N, McLennan S, Buyx A. Early Perceptions of COVID-19 contact tracing apps in german-speaking countries: comparative mixed methods study. J Med Internet Res. 2021;23(2):e25525. pmid:33503000
- 84. Al-Kuwari MG, Ali Al Nuaimi A, Semaan S, Gibb JM, AbdulMajeed J, Al Romaihi HE. Effectiveness of Ehteraz digital contact tracing app versus conventional contact tracing in managing the outbreak of COVID-19 in the State of Qatar. BMJ Innov. 2022;8(4):255–60.
- 85. Kendall M, Tsallis D, Wymant C, Di Francia A, Balogun Y, Didelot X, et al. Epidemiological impacts of the NHS COVID-19 app in England and Wales throughout its first year. Nat Commun. 2023;14(1):858. pmid:36813770
- 86. Khaliq KA, Noakes C, Kemp AH, Thompson C, CONTACT Trial Team. Evaluating the performance of wearable devices for contact tracing in care home environments. J Occup Environ Hyg. 2023;20(10):468–79. pmid:37540215
- 87. Ishimaru T, Ibayashi K, Nagata M, Hino A, Tateishi S, Tsuji M, et al. Industry and workplace characteristics associated with the downloading of a COVID-19 contact tracing app in Japan: a nation-wide cross-sectional study. Environ Health Prev Med. 2021;26(1):94. pmid:34548033
- 88. Rodríguez P, Graña S, Alvarez-León EE, Battaglini M, Darias FJ, Hernán MA, et al. A population-based controlled experiment assessing the epidemiological impact of digital contact tracing. Nat Commun. 2021;12(1):587. pmid:33500407
- 89. Contact Transmission of COVID-19 in South Korea: Novel Investigation Techniques for Tracing Contacts. Osong Public Health Res Perspect. 2020;11: 60–63.
- 90. Kim T, Park E, Eun JS, Lee E-Y, Mun JW, Choi Y, et al. Detecting mpox infection in the early epidemic: an epidemiologic investigation of the third and fourth cases in Korea. Epidemiol Health. 2023;45:e2023040. pmid:36996865
- 91. Gong S, Moon JY, Jung J. Perceived usefulness of COVID-19 tools for contact tracing among contact tracers in Korea. Epidemiol Health. 2022;44:e2022106. pmid:36397242
- 92. Kang S-J, Kim S, Park K-H, Jung SI, Shin M-H, Kweon S-S, et al. Successful control of COVID-19 outbreak through tracing, testing, and isolation: Lessons learned from the outbreak control efforts made in a metropolitan city of South Korea. J Infect Public Health. 2021;14(9):1151–4. pmid:34364306
- 93. Manavi K, Bhaduri S, Tariq A, West Midlands British Association of Sexual Health Audit Group. Audit on the success of partner notification for sexually transmitted infections in the West Midlands. Int J STD AIDS. 2008;19(12):856–8. pmid:19050219
- 94. Velhal GD, Shah AK, Dhanusu S. Contact Tracing for COVID-19 among health-care workers of a tertiary care hospital in Mumbai. Indian J Community Med. 2022;47(3):420–4. pmid:36438541
- 95. Brewer DD, Hagan H. Evaluation of a patient referral contact tracing programme for hepatitis B and C virus infection in drug injectors. Euro Surveill. 2009;14(14):5–9. pmid:19371508
- 96. Asiimwe N, Tabong PT-N, Iro SA, Noora CL, Opoku-Mensah K, Asampong E. Stakeholders perspective of, and experience with contact tracing for COVID-19 in Ghana: A qualitative study among contact tracers, supervisors, and contacts. PLoS One. 2021;16(2):e0247038. pmid:33571296
- 97. Sevimli S, Sevimli BS. Challenges and ethical issues related to COVID-19 contact tracing teams in Turkey. J Multidiscip Healthc. 2021;14:3151–9. pmid:34803383
- 98. Macomber K, Hill A, Coyle J, Davidson P, Kuo J, Lyon-Callo S. Centralized COVID-19 contact tracing in a home-rule State. Public Health Rep. 2022;137(2):35S-39S. pmid:35699392
- 99. Mandalakas AM, Ngo K, Alonso Ustero P, Golin R, Anabwani F, Mzileni B, et al. BUTIMBA: intensifying the hunt for child TB in Swaziland through household contact tracing. PLoS One. 2017;12(1):e0169769. pmid:28107473
- 100. Greiner AL, Angelo KM, McCollum AM, Mirkovic K, Arthur R, Angulo FJ. Addressing contact tracing challenges-critical to halting Ebola virus disease transmission. Int J Infect Dis. 2015;41:53–5. pmid:26546808
- 101. Chung WM, Smith JC, Weil LM, Hughes SM, Joyner SN, Hall EM, et al. Active tracing and monitoring of contacts associated with the first cluster of Ebola in the United States. Ann Intern Med. 2015;163(3):164–73. pmid:26005809
- 102. Stuart RL, Zhu W, Morand EF, Stripp A. Breaking the chain of transmission within a tertiary health service: An approach to contact tracing during the COVID-19 pandemic. Infect Dis Health. 2021;26(2):118–22. pmid:33281108
- 103. Karosas A, Ye L. Challenges of contact tracing in college students during COVID-19 pandemic. J Am Coll Health. 2024;72(5):1317–20. pmid:35658123
- 104. Swanson KC, Altare C, Wesseh CS, Nyenswah T, Ahmed T, Eyal N, et al. Contact tracing performance during the Ebola epidemic in Liberia, 2014-2015. PLoS Negl Trop Dis. 2018;12(9):e0006762. pmid:30208032
- 105. Ringshausen FC, Schlösser S, Nienhaus A, Schablon A, Schultze-Werninghaus G, Rohde G. In-hospital contact investigation among health care workers after exposure to smear-negative tuberculosis. J Occup Med Toxicol. 2009;4:11. pmid:19505310
- 106. Cordery R, Purba AK, Begum L, Mills E, Mosavie M, Vieira A, et al. Frequency of transmission, asymptomatic shedding, and airborne spread of Streptococcus pyogenes in schoolchildren exposed to scarlet fever: a prospective, longitudinal, multicohort, molecular epidemiological, contact-tracing study in England, UK. Lancet Microbe. 2022;3(5):e366–75. pmid:35544097
- 107. Trueba F, Haus-Cheymol R, Koeck J-L, Nombalier Y, Ceyriac A, Boiron S, et al. Contact tracing in a case of tuberculosis in a health care worker. Rev Mal Respir. 2006;23(4 Pt 1):339–42. pmid:17127909
- 108. Hoang TTT, Nguyen VN, Dinh NS, Thwaites G, Nguyen TA, van Doorn HR, et al. Active contact tracing beyond the household in multidrug resistant tuberculosis in Vietnam: a cohort study. BMC Public Health. 2019;19(1):241. pmid:30819161
- 109. Njuguna C, Vandi M, Liyosi E, Githuku J, Wurie A, Njeru I, et al. A challenging response to a Lassa fever outbreak in a non endemic area of Sierra Leone in 2019 with export of cases to The Netherlands. Int J Infect Dis. 2022;117:295–301. pmid:35167968
- 110. Stout JE, Katrak S, Goswami ND, Norton BL, Fortenberry ER, Foust E, et al. Integrated screening for tuberculosis and HIV in tuberculosis contact investigations: lessons learned in North Carolina. Public Health Rep. 2014;129 Suppl 1(Suppl 1):21–5. pmid:24385645
- 111. Gordon CL, Trubiano JA, Holmes NE, Chua KYL, Feldman J, Young G, et al. Staff to staff transmission as a driver of healthcare worker infections with COVID-19. Infect Dis Health. 2021;26(4):276–83. pmid:34344634
- 112. Kanu FA, Smith EE, Offutt-Powell T, Hong R, Delaware Case Investigation and Contact Tracing Teams3, Dinh T-H, et al. Declines in SARS-CoV-2 transmission, hospitalizations, and mortality after implementation of mitigation measures- Delaware, March-June 2020. MMWR Morb Mortal Wkly Rep. 2020;69(45):1691–4. pmid:33180757
- 113. Huang P-Y, Wu T-S, Cheng C-W, Chen C-J, Huang C-G, Tsao K-C, et al. A hospital cluster of COVID-19 associated with a SARS-CoV-2 superspreading event. J Microbiol Immunol Infect. 2022;55(3):436–44. pmid:34334353
- 114. de Laval F, Grosset-Janin A, Delon F, Allonneau A, Tong C, Letois F, et al. Lessons learned from the investigation of a COVID-19 cluster in Creil, France: effectiveness of targeting symptomatic cases and conducting contact tracing around them. BMC Infect Dis. 2021;21(1):457. pmid:34011278
- 115. Kang M, Song T, Zhong H, Hou J, Wang J, Li J, et al. Contact tracing for imported case of middle east respiratory syndrome, China, 2015. Emerg Infect Dis. 2016;22(9):1644–6. pmid:27532887
- 116. Quach H-L, Nguyen KC, Hoang N-A, Pham TQ, Tran DN, Le MTQ, et al. Association of public health interventions and COVID-19 incidence in Vietnam, January to December 2020. Int J Infect Dis. 2021;110(1):S28–43. pmid:34332082
- 117. Cheng VC-C, Siu GK-H, Wong S-C, Au AK-W, Ng CS-F, Chen H, et al. Complementation of contact tracing by mass testing for successful containment of beta COVID-19 variant (SARS-CoV-2 VOC B.1.351) epidemic in Hong Kong. Lancet Reg Health West Pac. 2021;17:100281. pmid:34611629
- 118. Udeagu C-CN, Huang J, Misra K, Terilli T, Ramos Y, Alexander M, et al. Community-based workforce for COVID-19 contact tracing and prevention activities in New York City, July-December 2020. Public Health Rep. 2022;137(2):46S-50S. pmid:35861302
- 119. Estcourt CS, Sutcliffe LJ, Copas A, Mercer CH, Roberts TE, Jackson LJ, et al. Developing and testing accelerated partner therapy for partner notification for people with genital Chlamydia trachomatis diagnosed in primary care: a pilot randomised controlled trial. Sex Transm Infect. 2015;91(8):548–54. pmid:26019232
- 120. Cope AB, Bernstein KT, Matthias J, Rahman M, Diesel JC, Pugsley RA, et al. Effectiveness of syphilis partner notification after adjusting for treatment dates, 7 jurisdictions. Sex Transm Dis. 2022;49(2):160–5. pmid:34310526
- 121. Montagni I, Roussel N, Thiébaut R, Tzourio C. Health care students’ knowledge of and attitudes, beliefs, and practices toward the french COVID-19 App: cross-sectional questionnaire study. J Med Internet Res. 2021;23(3):e26399. pmid:33566793
- 122. Shelby T, Hennein R, Schenck C, Clark K, Meyer AJ, Goodwin J, et al. Implementation of a volunteer contact tracing program for COVID-19 in the United States: a qualitative focus group study. PLoS One. 2021;16(5):e0251033. pmid:33951107
- 123. Shaikh BT, Laghari AK, Durrani S, Chaudhry A, Ali N. Supporting tuberculosis program in active contact tracing: a case study from Pakistan. Infect Dis Poverty. 2022;11(1):42. pmid:35397556
- 124. Bianchini S, Rigotti E, Monaco S, Nicoletti L, Auriti C, Castagnola E, et al. Surgical antimicrobial prophylaxis in abdominal surgery for neonates and paediatrics: a RAND/UCLA appropriateness method consensus study. Antibiotics (Basel). 2022;11(2):279. pmid:35203881
- 125. Feuerstein-Simon R, Strelau KM, Naseer N, Claycomb K, Kilaru A, Lawman H, et al. Design, implementation, and outcomes of a volunteer-staffed case investigation and contact tracing initiative at an urban academic medical center. JAMA Netw Open. 2022;5(9):e2232110. pmid:36149656
- 126. Zirbes J, Sterr CM, Steller M, Dapper L, Nonnenmacher-Winter C, Günther F. Development of a web-based contact tracing and point-of-care-testing workflow for SARS-CoV-2 at a German University Hospital. Antimicrob Resist Infect Control. 2021;10(1):102. pmid:34215330
- 127. Eames KTD, Webb C, Thomas K, Smith J, Salmon R, Temple JMF. Assessing the role of contact tracing in a suspected H7N2 influenza A outbreak in humans in Wales. BMC Infect Dis. 2010;10:141. pmid:20509927
- 128. Götz HM, van Doornum G, Niesters HG, den Hollander JG, Thio HB, de Zwart O. A cluster of acute hepatitis C virus infection among men who have sex with men--results from contact tracing and public health implications. AIDS. 2005;19(9):969–74. pmid:15905679
- 129. Yaşar Durmuş S, Tanır G, Aydın Teke T, Kaman A, Yalçınkaya R, Üner Ç, et al. Tuberculosis contact-tracing results in childhood: a retrospective study in a tertiary-care children’s hospital in Turkey. Paediatr Int Child Health. 2023;43(1–3):5–12. pmid:37671805
- 130. Aronoff-Spencer E, Nebeker C, Wenzel AT, Nguyen K, Kunowski R, Zhu M, et al. Defining Key Performance Indicators for the California COVID-19 Exposure Notification System (CA Notify). Public Health Rep. 2022;137(2_suppl):67S-75S. pmid:36314660
- 131. Horvath L, Banducci S, Blamire J, Degnen C, James O, Jones A, et al. Adoption and continued use of mobile contact tracing technology: multilevel explanations from a three-wave panel survey and linked data. BMJ Open. 2022;12(1):e053327. pmid:35039293
- 132. Kelly AM, D’Agostino JF, Andrada LV, Liu J, Larson E. Delayed tuberculosis diagnosis and costs of contact investigations for hospital exposure: New York City, 2010-2014. Am J Infect Control. 2017;45(5):483–6. pmid:28216248
- 133. Goroh MMD, van den Boogaard CHA, Lukman KA, Lowbridge C, Juin WK, William T, et al. Factors affecting implementation of tuberculosis contact investigation and tuberculosis preventive therapy among children in Sabah, East Malaysia: A qualitative study. PLoS One. 2023;18(5):e0285534. pmid:37167225
- 134. Liippo KK, Kulmala K, Tala EO. Focusing tuberculosis contact tracing by smear grading of index cases. Am Rev Respir Dis. 1993;148(1):235–6. pmid:8317806
- 135. Vella V, Racalbuto V, Guerra R, Marra C, Moll A, Mhlanga Z, et al. Household contact investigation of multidrug-resistant and extensively drug-resistant tuberculosis in a high HIV prevalence setting. Int J Tuberc Lung Dis. 2011;15(9):1170–5, i. pmid:21943840
- 136. Steinmann P, Cavaliero A, Aerts A, Anand S, Arif M, Ay SS, et al. The Leprosy Post-Exposure Prophylaxis (LPEP) programme: update and interim analysis. Lepr Rev. 2018;89(2):102–16. pmid:37180343
- 137. Parvaresh L, Bag SK, Cho J-G, Heron N, Assareh H, Norton S, et al. Monitoring tuberculosis contact tracing outcomes in Western Sydney, Australia. BMJ Open Respir Res. 2018;5(1):e000341. pmid:30397487
- 138. Hernán García C, Moreno Cea L, Fernández Espinilla V, Ruiz Lopez Del Prado G, Fernández Arribas S, Andrés García I, et al. Outbreak of isoniazid-resistant tuberculosis in an immigrant community in Spain. Arch Bronconeumol. 2016;52(6):289–92. pmid:26584529
- 139. Paryani RH, Gupta V, Singh P, Verma M, Sheikh S, Yadav R, et al. Yield of systematic longitudinal screening of household contacts of Pre-Extensively Drug Resistant (PreXDR) and Extensively Drug Resistant (XDR) tuberculosis patients in Mumbai, India. Trop Med Infect Dis. 2020;5(2):83. pmid:32466438
- 140. DePhilippis D, Metzger DS, Woody GE, Navaline HA. Attitudes toward mandatory human immunodeficiency virus testing and contact tracing. A survey of intravenous drug users in treatment. J Subst Abuse Treat. 1992;9(1):39–42. pmid:1593663
- 141. Imsanguan W, Bupachat S, Wanchaithanawong V, Luangjina S, Thawtheong S, Nedsuwan S, et al. Contact tracing for tuberculosis, Thailand. Bull World Health Organ. 2020;98(3):212–8. pmid:32132756
- 142. Eckhardt B, Aponte-Melendez Y, Kapadia SN, Mateu-Gelabert P. Contact tracing in acute hepatitis C: The source patient identification and group overlap therapy proof-of-concept pilot program. Clin Liver Dis (Hoboken). 2022;20(2):72–6. pmid:36033428
- 143. Hanrahan CF, Nonyane BAS, Mmolawa L, West NS, Siwelana T, Lebina L, et al. Contact tracing versus facility-based screening for active TB case finding in rural South Africa: A pragmatic cluster-randomized trial (Kharitode TB). PLoS Med. 2019;16(4):e1002796. pmid:31039165
- 144. Tefera F, Barnabee G, Sharma A, Feleke B, Atnafu D, Haymanot N, et al. Evaluation of facility and community-based active household tuberculosis contact investigation in Ethiopia: a cross-sectional study. BMC Health Serv Res. 2019;19(1):234. pmid:31010427
- 145. Pasquale DK, Welsh W, Olson A, Yacoub M, Moody J, Barajas Gomez BA, et al. Scalable strategies to increase efficiency and augment public health activities during epidemic peaks. J Public Health Manag Pract. 2023;29(6):863–73. pmid:37379511
- 146. Mouter N, Collewet M, de Wit GA, Rotteveel A, Lambooij MS, Kessels R. Societal effects are a major factor for the uptake of the coronavirus disease 2019 (COVID-19) digital contact tracing app in The Netherlands. Value Health. 2021;24(5):658–67. pmid:33933234
- 147. André E, Rusumba O, Evans CA, Ngongo P, Sanduku P, Elvis MM, et al. Patient-led active tuberculosis case-finding in the Democratic Republic of the Congo. Bull World Health Organ. 2018;96(8):522–30. pmid:30104792
- 148. Munzert S, Selb P, Gohdes A, Stoetzer LF, Lowe W. Tracking and promoting the usage of a COVID-19 contact tracing app. Nat Hum Behav. 2021;5(2):247–55. pmid:33479505
- 149. Ayalon O, Li S, Preneel B, Redmiles EM. Not only for contact tracing. Proc ACM Interact Mob Wearable Ubiquitous Technol. 2022;6(4):1–26.
- 150. Pelton M, Medina D, Sood N, Bogale K, Buzzelli L, Blaker J, et al. Efficacy of a student-led community contact tracing program partnered with an academic medical center during the coronavirus disease 2019 pandemic. Ann Epidemiol. 2021;56:26-33.e1. pmid:33775279
- 151. Rebmann T, Loux TM, Gomel A, Lugo KA, Bafageeh F, Elkins H, et al. Assessing classroom and laboratory spread of COVID-19 in a university after elimination of physical distancing. PLoS One. 2023;18(3):e0283050. pmid:36928029
- 152. Blaney K, Foerster S, Baumgartner J, Benckert M, Blake J, Bray J, et al. COVID-19 case investigation and contact tracing in New York City, June 1, 2020, to October 31, 2021. JAMA Netw Open. 2022;5(11):e2239661. pmid:36322090
- 153. Lubogo M, Donewell B, Godbless L, Shabani S, Maeda J, Temba H, et al. Ebola virus disease outbreak; the role of field epidemiology training programme in the fight against the epidemic, Liberia, 2014. Pan Afr Med J. 2015;22 Suppl 1(Suppl 1):5. pmid:26779298
- 154. Kern D, Tabidze I, Modali L, Stonehouse P, Karamustafa A. Unified Response to COVID-19 case investigation and contact tracing, Chicago, December 2020-April 2021. Public Health Rep. 2022;137(2_suppl):40S-45S. pmid:36314690
- 155. Harrington KRV, Siira MR, Rothschild EP, Rabinovitz SR, Shartar S, Clark D, et al. A university-led contact tracing program response to a COVID-19 outbreak among students in Georgia, February-March 2021. Public Health Rep. 2022;137(2_suppl):61S-66S. pmid:35989589
- 156. Lu LC, Ouyang D, D’Agostino A, Diaz A, Rudman SL, Ho DE. Integrating social services with disease investigation: a randomized trial of COVID-19 high-touch contact tracing. PLoS One. 2023;18(5):e0285752. pmid:37192191
- 157. Wu X, Hong F, Zhang C, Feng T, Lan L, Yang Y. Contact tracing of pregnant women infected with syphilis and the associated factors. Zhonghua Yu Fang Yi Xue Za Zhi. 2015;49(12):1067–72. pmid:26887301
- 158. Tesfaye L, Lemu YK, Tareke KG, Chaka M, Feyissa GT. Exploration of barriers and facilitators to household contact tracing of index tuberculosis cases in Anlemo district, Hadiya zone, Southern Ethiopia: Qualitative study. PLoS One. 2020;15(5):e0233358. pmid:32442201
- 159. Harvard Global Health Institute, Edmond J. Safra Center for Ethics. Key Metrics for COVID Suppression. A Framework for policy makers and the public. 2020. Available from: https://ethics.harvard.edu/sites/hwpi.harvard.edu/files/center-for-ethics/files/key_metrics_and_indicators_v4.pdf?m=1593600837
- 160. Hong P, Herigon JC, Uptegraft C, Samuel B, Brown DL, Bickel J, et al. Use of clinical data to augment healthcare worker contact tracing during the COVID-19 pandemic. J Am Med Inform Assoc. 2021;29(1):142–8. pmid:34623426
- 161. Mulder C, Harting J, Jansen N, Borgdorff MW, van Leth F. Adherence by Dutch public health nurses to the national guidelines for tuberculosis contact investigation. PLoS One. 2012;7(11):e49649. pmid:23166738
- 162. Osterlund A, Persson T, Persson I, Lysén M, Herrmann B. Improved contact tracing of Chlamydia trachomatis in a Swedish county--is genotyping worthwhile?. Int J STD AIDS. 2005;16(1):9–13. pmid:15705265
- 163. Svoboda T, Henry B, Shulman L, Kennedy E, Rea E, Ng W, et al. Public health measures to control the spread of the severe acute respiratory syndrome during the outbreak in Toronto. N Engl J Med. 2004;350(23):2352–61. pmid:15175437
- 164. Senga M, Koi A, Moses L, Wauquier N, Barboza P, Fernandez-Garcia MD, et al. Contact tracing performance during the Ebola virus disease outbreak in Kenema district, Sierra Leone. Philos Trans R Soc Lond B Biol Sci. 2017;372(1721):20160300. pmid:28396471
- 165. Dixon MG, Taylor MM, Dee J, Hakim A, Cantey P, Lim T, et al. Contact Tracing Activities during the Ebola Virus Disease Epidemic in Kindia and Faranah, Guinea, 2014. Emerg Infect Dis. 2015;21(11):2022–8. pmid:26488116
- 166. Richardus JH, Meima A, van Marrewijk CJ, Croft RP, Smith TC. Close contacts with leprosy in newly diagnosed leprosy patients in a high and low endemic area: comparison between Bangladesh and Thailand. Int J Lepr Other Mycobact Dis. 2005;73(4):249–57. pmid:16830634
- 167. Laxminarayan R, Wahl B, Dudala SR, Gopal K, Mohan B C, Neelima S, et al. Epidemiology and transmission dynamics of COVID-19 in two Indian states. Science. 2020;370(6517):691–7. pmid:33154136
- 168. . Population-based analysis of the epidemiological features of COVID-19 epidemics in Victoria, Australia, January 2020 - March 2021, and their suppression through comprehensive control strategies. Lancet Reg Health West Pac. 2021;17:100297. pmid:34723232
- 169. Proesmans K, Hancart S, Braeye T, Klamer S, Robesyn E, Djiena A, et al. COVID-19 contact tracing in Belgium: main indicators and performance, January - September 2021. Arch Public Health. 2022;80(1):118. pmid:35418097
- 170. Vaughn J, Karayeva E, Lopez-Yanez N, Stein EM, Hershow RC. Implementation and effectiveness of a COVID-19 case investigation and contact tracing program at a large, urban midwestern university. Am J Infect Control. 2023;51(3):268–75. pmid:36804098
- 171. Yalaman A, Basbug G, Elgin C, Galvani AP. Cross-country evidence on the association between contact tracing and COVID-19 case fatality rates. Sci Rep. 2021;11(1):2145. pmid:33495491
- 172. Fernández-Niño JA, Peña-Maldonado C, Rojas-Botero M, Rodriguez-Villamizar LA. Effectiveness of contact tracing to reduce fatality from COVID-19: preliminary evidence from Colombia. Public Health. 2021;198:123–8. pmid:34416575
- 173. Sinha LN, Bodat S, Kaur D, Tanwar D, Deep A, Mathur A, et al. Challenges in contact tracing and sampling in three districts of western rajasthan during the COVID-19 pandemic | semantic scholar. Indian Journal of Public Health Research and Development. 2022 [cited 21 Nov 2023]. Available from: https://www.semanticscholar.org/paper/Challenges-in-Contact-Tracing-and-Sampling-in-Three-Sinha-Bodat/64de608e9f743072a31064fa5bfa9b2ea63ddf65
- 174. Noertjojo K, Tam CM, Chan SL, Tan J, Chan-Yeung M. Contact examination for tuberculosis in Hong Kong is useful. Int J Tuberc Lung Dis. 2002;6(1):19–24. pmid:11931396
- 175. Jaganath D, Zalwango S, Okware B, Nsereko M, Kisingo H, Malone L, et al. Contact investigation for active tuberculosis among child contacts in Uganda. Clin Infect Dis. 2013;57(12):1685–92. pmid:24077055
- 176. Ling D-L, Liaw Y-P, Lee C-Y, Lo H-Y, Yang H-L, Chan P-C. Contact investigation for tuberculosis in Taiwan contacts aged under 20 years in 2005. Int J Tuberc Lung Dis. 2011;15(1):50–5. pmid:21276296
- 177. Kadyrov M, Thekkur P, Geliukh E, Sargsyan A, Goncharova O, Kulzhabaeva A, et al. Contact tracing and tuberculosis preventive therapy for household child contacts of pulmonary tuberculosis patients in the Kyrgyz republic: how well are we doing?. Trop Med Infect Dis. 2023;8(7):332. pmid:37505628
- 178. Nair D, Rajshekhar N, Klinton JS, Watson B, Velayutham B, Tripathy JP, et al. Household contact screening and yield of tuberculosis cases-a clinic based study in Chennai, South India. PLoS One. 2016;11(9):e0162090. pmid:27583974
- 179. Teherani MF, Kao CM, Camacho-Gonzalez A, Banskota S, Shane AL, Linam WM, et al. Burden of illness in households with severe acute respiratory syndrome coronavirus 2-infected children. J Pediatric Infect Dis Soc. 2020;9(5):613–6. pmid:32780809
- 180. Wolfe CM, Hamblion EL, Schulte J, Williams P, Koryon A, Enders J, et al. Ebola virus disease contact tracing activities, lessons learned and best practices during the Duport Road outbreak in Monrovia, Liberia, November 2015. PLoS Negl Trop Dis. 2017;11(6):e0005597. pmid:28575034
- 181. Somda SMA, Ouedraogo B, Pare CB, Kouanda S. Estimation of the serial interval and the effective reproductive number of COVID-19 outbreak using contact data in burkina Faso, a Sub-Saharan African country. Comput Math Methods Med. 2022;2022:8239915. pmid:36199779
- 182. Moyo N, Tay EL, Denholm JT. Evaluation of tuberculin skin testing in tuberculosis contacts in Victoria, Australia, 2005-2013. Public Health Action. 2015;5(3):188–93. pmid:26399290
- 183. Glasauer S, Kröger S, Haas W, Perumal N. International tuberculosis contact-tracing notifications in Germany: analysis of national data from 2010 to 2018 and implications for efficiency. BMC Infect Dis. 2020;20(1):267. pmid:32252650
- 184. Swaan CM, Appels R, Kretzschmar MEE, van Steenbergen JE. Timeliness of contact tracing among flight passengers for influenza A/H1N1 2009. BMC Infect Dis. 2011;11:355. pmid:22204494
- 185. Bitzegeio J, Bukowski B, Hausner M, Sissolak D, Rasmussen LD, Andersen PH, et al. Two measles clusters in connection with short inner-European air travels indicating impediments to effective measles control: a cluster analysis. Travel Med Infect Dis. 2020;33:101542. pmid:31786281
- 186. Amisi JA, Carter EJ, Masini E, Szkwarko D. Closing the loop in child TB contact management: completion of TB preventive therapy outcomes in western Kenya. BMJ Open. 2021;11(2):e040993. pmid:33622944
- 187. Said D, Brinkwirth S, Taylor A, Markwart R, Eckmanns T. The containment scouts: first insights into an initiative to increase the public health workforce for contact tracing during the COVID-19 pandemic in Germany. Int J Environ Res Public Health. 2021;18(17):9325. pmid:34501912
- 188. Braga JM, Banze AR, Dengo-Baloi L, Evaristo VL, Rossetto EV, Baltazar CS. Investigation and contact tracing of the first cases of COVID-19 in Mozambique, 2020. Pan Afr Med J. 2022;41:302. pmid:35855024
- 189. Markus I, Steffen G, Lachmann R, Marquis A, Schneider T, Tomczyk S, et al. COVID-19: cross-border contact tracing in Germany, February to April 2020. Euro Surveill. 2021;26(10):2001236. pmid:33706859
- 190. Barrett PM, Bambury N, Kelly L, Condon R, Crompton J, Sheahan A, et al. Measuring the effectiveness of an automated text messaging active surveillance system for COVID-19 in the south of Ireland, March to April 2020. Euro Surveill. 2020;25(23):2000972. pmid:32553064
- 191. Hoang PA, Tran NT, Nguyen THH, Nguyen TTH. Barriers to COVID-19 contact tracing: view from frontline healthcare students in Vietnam. Public Health Nurs. 2023;40(4):528–34. pmid:36938938
- 192. Dubey P, Das A, Priyamvada K, Bindroo J, Mahapatra T, Mishra PK, et al. Development and evaluation of active case detection methods to support visceral Leishmaniasis Elimination in India. Front Cell Infect Microbiol. 2021;11:648903. pmid:33842396
- 193. Pihlajamäki M, Wickström S, Puranen K, Helve O, Yrttiaho A, Siira L. Implementing and maintaining a SARS-CoV-2 exposure notification application for mobile phones: the finnish experience. JMIR Public Health Surveill. 2023;9:e46563. pmid:37440286
- 194. Woodward A, Rivers C. Building case investigation and contact tracing programs in U.S. state and local health departments: a conceptual framework. Public and Global Health. 2023.
- 195. So H, Kim KM, Bae EY, Cho EY. A measles outbreak in a local children’s hospital in Korea, 2019. J Korean Med Sci. 2023;38(3):e28. pmid:36647221
- 196. Feldman KA, Hanks A, Williams TW, Blouse B, Babcock C, Goode A, et al. A state health department and health information exchange partnership: an effective collaboration for a data-driven response for COVID-19 contact tracing in maryland. Sex Transm Dis. 2023;50(8S Suppl 1):S34–40. pmid:36098564
- 197. Nasomsong W, Changpradub D, Vasikasin V. Effectiveness and resource utilization of hospital-based contact tracing of patients and health care workers with COVID-19 at a tertiary teaching hospital in Thailand. Clinical Epidemiology and Global Health. 2023;23:101365.
- 198. Ussai S, Pistis M, Missoni E, Formenti B, Armocida B, Pedrazzi T, et al. “Immuni” and the national health system: lessons learnt from the COVID-19 digital contact tracing in Italy. Int J Environ Res Public Health. 2022;19(12):7529. pmid:35742778
- 199. Asare IT, Douglas M, Kye-Duodu G, Manu E. Challenges and opportunities for improved contact tracing in Ghana: experiences from Coronavirus disease-2019-related contact tracing in the Bono region. BMC Infect Dis. 2023;23(1):335. pmid:37202733
- 200. Fawole OI, Bello S, Adebowale AS, Bamgboye EA, Salawu MM, Afolabi RF, et al. COVID-19 surveillance in democratic Republic of Congo, Nigeria, Senegal and Uganda: strengths, weaknesses and key Lessons. BMC Public Health. 2023;23(1):835. pmid:37158897
- 201. Tsang KK, Ahmad S, Aljarbou A, Al Salem M, Baker SJC, Panousis EM, et al. SARS-CoV-2 outbreak investigation using contact tracing and whole-genome sequencing in an ontario tertiary care hospital. Microbiol Spectr. 2023;11(3):e0190022. pmid:37093060
- 202. Liu H, Liang Z, Zhang S, Liu L. Sociodemographic and Policy Factors Associated with the Transmission of COVID-19: Analyzing longitudinal contact tracing data from a northern Chinese city. J Urban Health. 2022;99(3):582–93. pmid:35641716
- 203. Lee D, Choi B. Policies and innovations to battle Covid-19 - A case study of South Korea. Health Policy Technol. 2020;9(4):587–97. pmid:32874856
- 204. Sturrock HJW, Novotny JM, Kunene S, Dlamini S, Zulu Z, Cohen JM, et al. Reactive case detection for malaria elimination: real-life experience from an ongoing program in Swaziland. PLoS One. 2013;8(5):e63830. pmid:23700437
- 205. Danquah LO, Hasham N, MacFarlane M, Conteh FE, Momoh F, Tedesco AA, et al. Use of a mobile application for Ebola contact tracing and monitoring in northern Sierra Leone: a proof-of-concept study. BMC Infect Dis. 2019;19(1):810. pmid:31533659
- 206. Fähnrich C, Denecke K, Adeoye OO, Benzler J, Claus H, Kirchner G, et al. Surveillance and Outbreak Response Management System (SORMAS) to support the control of the Ebola virus disease outbreak in West Africa. Euro Surveill. 2015;20(12):21071. pmid:25846493
- 207. Hunter P, Oyervides O, Grande KM, Prater D, Vann V, Reitl I, et al. Facebook-augmented partner notification in a cluster of syphilis cases in Milwaukee. Public Health Rep. 2014;129 Suppl 1(Suppl 1):43–9. pmid:24385648
- 208. Dennis AM, Pasquale DK, Billock R, Beagle S, Mobley V, Cope A, et al. Integration of Contact tracing and phylogenetics in an Investigation of Acute HIV Infection. Sex Transm Dis. 2018;45(4):222–8. pmid:29465708
- 209. Mills A, Satin A. Measuring the outcome of contact tracing. 2. The responsibilities of the health worker and the outcome of contact investigations. Br J Vener Dis. 1978;54(3):192–8. pmid:656893
- 210. Winfield J, Latif AS. Tracing contacts of persons with sexually transmitted diseases in a developing country. Sex Transm Dis. 1985;12(1):5–7. pmid:3839096
- 211. Chitneni P, Beksinska M, Dietrich JJ, Jaggernath M, Closson K, Smith P, et al. Partner notification and treatment outcomes among South African adolescents and young adults diagnosed with a sexually transmitted infection via laboratory-based screening. Int J STD AIDS. 2020;31(7):627–36. pmid:32403988
- 212. Lal A, Ashworth HC, Dada S, Hoemeke L, Tambo E. Optimizing pandemic preparedness and response through health information systems: lessons learned from Ebola to COVID-19. Disaster Med Public Health Prep. 2022;16(1):333–40. pmid:33004102
- 213. Eichner L, Schlegel C, Roller G, Fischer H, Gerdes R, Sauerbrey F, et al. COVID-19 case findings and contact tracing in South German nursing homes. BMC Infect Dis. 2022;22(1):307. pmid:35351002
- 214. Kerbage A, Matta M, Haddad S, Daniel P, Tawk L, Gemayel S, et al. Challenges facing COVID-19 in rural areas: an experience from Lebanon. Int J Disaster Risk Reduct. 2021;53:102013. pmid:33318917
- 215. Aslam MA, Murtaza M, Zakar R, Rashid J. Insights from government officials on strategies and practices for managing the Covid-19 pandemic: a qualitative study. PJMHS. 2023;17(1):691–4.
- 216. O’Callaghan ME, Buckley J, Fitzgerald B, Johnson K, Laffey J, McNicholas B, et al. A national survey of attitudes to COVID-19 digital contact tracing in the Republic of Ireland. Ir J Med Sci. 2021;190(3):863–87. pmid:33063226
- 217. Abuhammad S, Khabour OF, Alzoubi KH. COVID-19 contact-tracing technology: acceptability and ethical issues of use. Patient Prefer Adherence. 2020;14:1639–47. pmid:32982188
- 218. Randolph W, Viswanath K. Lessons learned from public health mass media campaigns: marketing health in a crowded media world. Annu Rev Public Health. 2004;25:419–37. pmid:15015928
- 219. Vogt F, Kurup KK, Mussleman P, Habrun C, Crowe M, Woodward A, et al. Contact tracing indicators for COVID-19: Rapid scoping review and conceptual framework. PLoS One. 2022;17(2):e0264433. pmid:35226699
- 220. Islam MS, Vogt F, King C, Sheel M. COVID-19 contact tracing and quarantine policies in the Indo-Pacific Region: a mixed-methods study of experiences of public health professionals. PLOS Glob Public Health. 2024;4(5):e0003121. pmid:38820343
- 221. Ruebush E, Fraser MR, Poulin A, Allen M, Lane JT, Blumenstock JS. COVID-19 case investigation and contact tracing: early lessons learned and future opportunities. J Public Health Manag Pract. 2021;27(1):S87–97. pmid:33239569
