Integrating routine immunization into COVID-19 vaccination improve coverage but could create equity issues: evidence from Niger State, Nigeria

Abstract

Background

Integrating Routine Immunization (RI) into COVID-19 vaccination implies that COVID-19 vaccination is the primary focus, with RI services added to the effort. During COVID-19 vaccination campaigns in Nigeria, healthcare workers also provided routine vaccines such as measles and polio to individuals who came for their COVID-19 shots. This paper aims to demonstrate that integrating RI into COVID-19 vaccination increases overall vaccine coverage but may introduce equity issues.

Methodology

The data used in this study consist of COVID-19 immunization records (first, second, and booster doses) from 23 local government areas (LGAs) in Niger State, Nigeria. The project aimed to vaccinate the remaining 30% of the population who had not received any COVID-19 vaccine doses. Two LGAs were excluded due to security concerns. Routine immunizations (RIs) provided alongside COVID-19 vaccinations included the inactivated polio vaccine (IPV), oral polio vaccine (OPV), pentavalent polio vaccine (PENTA), and other vaccines based on specific needs, primarily targeting zero-dose children. The primary outcome was vaccine coverage, measured as the percentage of targeted individuals who received at least one dose of the COVID-19 vaccine. Secondary outcomes included the uptake of routine immunization during COVID-19 vaccination campaigns and a gender equity analysis to assess disparities in vaccination rates between males and females.

Results

A total of 436,598 individuals were vaccinated, with a daily average of 3,898. Among those vaccinated, 49.78% were male, while 50.22% were female, achieving a percentage coverage of 101%. Of the vaccinated individuals, 76% received a single dose, 5.1% received a second dose, and 18.3% received a booster dose. Among those who received a single dose, 49.9% were male and 50.1% were female. Among those who received the second dose, 47.4% were male and 52.6% were female. Among those who received the booster dose, 49.8% were male and 50.2% were female. No significant mean differences were found between males and females for those who received the first and booster doses. Similarly, there were no significant mean differences between the targeted and achieved vaccinations, despite variations in coverage across the 23 LGAs. Additionally, 60,373 routine immunizations were administered alongside COVID-19 vaccinations. A breakdown of the RI distribution showed that 17.6% of recipients received PENTA, 18.3% received OPV, 17.6% received IPV, and 46.5% received other vaccines. A significant mean difference was observed between males and females when RI was integrated into COVID-19 vaccinations, suggesting a gender disparity.

Conclusion

Although integrating RI into COVID-19 vaccination efforts increased overall immunization coverage, the data suggest potential inequities, as a higher proportion of RI doses were administered to females. This finding highlights differences in vaccine access between males and females. Further research is needed to understand the impact of gender differences in RI integration and to promote equitable vaccination access for all.

Background

The vaccination of people against COVID-19 remains a priority in the post-pandemic era. One key strategy adopted to enhance COVID-19 vaccination coverage is the integration of routine immunization (RI). Integrating RI into COVID-19 vaccination considered in this paper implies that COVID-19 vaccination is the primary focus, with RI services added to the effort. During COVID-19 vaccination campaigns in Nigeria, healthcare workers also provided routine vaccines such as measles and polio to individuals who came for their COVID-19 shots. This approach is based on the premise that integration can improve access to and coverage of both vaccines, reduce costs and operational complexity, and reach subpopulations that might otherwise be missed by separate vaccination models [1]. Several studies across Africa [2] and other continents [3] have demonstrated the feasibility and effectiveness of this strategy, reporting significant increases in COVID-19 vaccination coverage and higher vaccine uptake among children, adolescents, caregivers, and parents.

Despite these efforts, Nigeria has faced challenges in meeting its global COVID-19 vaccination targets. The country aimed to vaccinate 40% of its population by the end of 2021 and reach the 70% threshold before the end of 2022. However, these goals were not met due to factors such as cold-chain and supply chain management issues, distrust in government intentions, low awareness levels, and cultural, political, and religious influences [4]. Nigeria launched its COVID-19 vaccination program in March 2021 with the AstraZeneca/Oxford vaccine through the COVAX facility, marking its largest vaccination effort to date. The initial phase prioritized frontline healthcare workers, and since then, the country has received over 67 million vaccine doses from various sources, leading to the full vaccination of 35.1 million individuals. The World Health Organization (WHO) defines “fully vaccinated” as having completed the primary series of a COVID-19 vaccine approved for emergency use or fully licensed by WHO or a stringent regulatory authority. Nigeria has subsequently approved six other vaccines, including Moderna, Pfizer/BioNTech, Gamaleya, Janssen, the Serum Institute of India vaccine, and Sinopharm [5]. As of March 2, 2023, a total of 68,901,179 individuals (59.4% of the eligible population aged 18 and above) were fully vaccinated, representing 28.7% of the total population. Additionally, 80,243,556 individuals (69.2% of the eligible population) had received at least one dose, accounting for 33.4% of the total population, while 12,114,360 (17.6%) of fully vaccinated persons had received a booster dose [6].

The growing coverage of COVID-19 vaccination in Nigeria has been largely attributed to effective collaboration among international agencies, donor organizations, the Nigerian government, and non-governmental organizations (NGOs) [7]. Various strategies have contributed to increased vaccination coverage, and one of the approaches explored in this paper is the integration of RI into COVID-19 vaccination.

Although different vaccination models including mass vaccination, mobile vaccination, and fixed-post vaccination have been implemented, there is limited literature on how RI integration has influenced these models in Nigeria. Furthermore, a recent systematic review found no documented evidence of RI integration in COVID-19 vaccination efforts in the country [8]. While one study [9] has reported integration, the scarcity of substantial literature motivated this research, which aims to examine how integrating RI into COVID-19 vaccination increases coverage. This paper highlights the use of integration in both antenatal and postnatal services at selected primary healthcare centers (PHCs) in Niger State, Nigeria. Notably, the integration of RI into COVID-19 vaccination for lactating women (postnatal) has not been previously reported in Nigeria.

Using incentives and reward systems has been shown to boost COVID-19 vaccination uptake [10]. However, it remains unclear how co-delivery with RI—such as the polio vaccine—has contributed to increased COVID-19 vaccine coverage, particularly regarding potential gender disparities in access. This study seeks to explore this aspect. The only documented example of co-delivery with RI in Nigeria is the administration of COVID-19 and influenza vaccines in school-located vaccine clinics targeting students and teachers [11]. Another example comes from a UNICEF-funded project in Iraq, where COVID-19 vaccines were integrated with diphtheria, tetanus, and pertussis vaccines [12]. However, both studies did not assess gender equity in vaccine access.

Integrating RI into COVID-19 vaccination has the potential to maximize vaccine coverage, reduce disparities, ensure equity among marginalized populations, build trust, and strengthen healthcare systems for future health crises [13]. This research will provide evidence that integrating RI into COVID-19 vaccination contributes to increased coverage. However, this approach may also introduce disparities in vaccine access, an issue that this paper will critically examine.

Methods

Study design

This study utilizes a retrospective cross-sectional design to analyze the impact of integrating routine immunization (RI) with COVID-19 vaccination in Niger State, Nigeria. The study aims to assess whether this integration increases vaccine coverage while also examining potential gender-based equity concerns.

Study setting and population

The study was conducted in 23 Local Government Areas (LGAs) of Niger State, Nigeria, between April and July 2023. Two LGAs were excluded due to security challenges. The study population includes individuals eligible for COVID-19 vaccination and children eligible for routine immunization within the intervention period.

Intervention/Project

The paper reports the analysis of data obtained from the immunization project in 23 LGAs of Niger State from April to July 2023. The project was funded by the United States Centers for Disease Control and Prevention (CDC), with Sydani Initiatives for International Development (SIID), Abuja, Nigeria, contracted to implement the initiative aimed at increasing COVID-19 vaccination uptake in the state. This was a continuation of the first phase of the vaccination exercise, which contributed to 23.8% of the 70% total vaccinations in the state from June to September 2022. Lessons learned from Phase I led to the adoption of mass vaccination, mobile vaccination, and fixed-post vaccination, supported by extensive public awareness campaigns to counter misinformation about COVID-19 vaccination. The project aimed to increase COVID-19 vaccination coverage by 20% of the eligible population while simultaneously administering routine immunizations. Key strategies included strengthening leadership and coordination structures, incentivizing vaccination teams, raising awareness through community sensitization, utilizing Kobo-collect for real-time reporting, and ensuring data triangulation across three reporting sources: EMID, Call-in, and Kobo-collect. To implement these strategies, 80 teams were trained across four clusters—Mokwa, Chanchaga, Kontagora, and Suleja—to cover all 23 LGAs. The training encompassed the use of Kobo-collect for data collection, understanding the EMID system and Call-in reporting, vaccination strategies, community engagement, security protocols, field safety, and data quality assurance. The project aimed to achieve 432,000 vaccinations within the stipulated timeframe, covering the remaining 20% of the unvaccinated population. However, the remaining 10% could not be reached due to security concerns in two LGAs.

Delivery of COVID-19 and routine immunization antigens

Some of the 80 vaccination teams co-delivered COVID-19 vaccines alongside routine immunization (RI) antigens, including inactivated polio vaccine (IPV), oral polio vaccine (OPV), pentavalent vaccine (PENTA), and others. Routine immunization efforts targeted zero-dose children and included vaccines for hepatitis B virus (HBV), hepatitis A virus (HAV), pertussis, varicella (chickenpox), yellow fever, rotavirus, and measles. The vaccinations were administered according to the national guidelines of the National Primary Healthcare Development Agency (NPHCDA) on the integration of health services. Through collaboration with the Niger State Primary Healthcare Development Agency, SIID successfully reached all 23 LGAs. Some teams strategically used RI as an entry point to increase COVID-19 coverage while simultaneously addressing gaps in routine immunization that had widened due to the COVID-19 pandemic.

Data collection and management

The project employed a structured approach to data collection and management to ensure accurate and timely reporting of vaccination coverage. The data collection process was integrated across three platforms: EMID, Call-in, and Kobo-collect, allowing for efficient triangulation and validation of reported figures. Kobo-collect was used at all levels to facilitate real-time data entry and monitoring, reducing errors and enhancing transparency in reporting. Vaccination teams received extensive training on data collection procedures, including the proper use of Kobo-collect, EMID system reporting, and Call-in documentation to ensure uniformity in data capture. The project also implemented data quality assurance measures, including field supervision, routine data verification, and cross-checking of vaccination records to minimize discrepancies. Additionally, data from routine immunization services were incorporated into the reporting system to provide a holistic view of immunization coverage. Collaboration with the Niger State Primary Healthcare Development Agency ensured seamless data flow between vaccination teams and government health records, supporting efforts to close immunization gaps and enhance decision-making for future vaccination campaigns.

Outcome measures

The primary outcome of the project was vaccine coverage, measured as the percentage of targeted individuals who received at least one dose of the COVID-19 vaccine. Secondary outcomes included the uptake of routine immunization during COVID-19 vaccination campaigns and a gender equity analysis of vaccine uptake to assess disparities in vaccination rates between males and females.

Statistical analysis

Data were analyzed using SPSS version 25 and R software version 4.2. Descriptive statistics were used to determine the frequencies and proportions of vaccinated individuals by gender and vaccine type. T-tests were conducted to assess gender disparities in vaccine uptake, while significance testing was performed using p-values at thresholds of 0.05 and 0.001 to determine statistical significance.

Result

Summary of vaccination

Eighty (80) teams reported 4468 times (vaccination data) over 16 weeks, or 112 days, across the 23 LGAs of Nigeria State. The summary of the gender distribution for those who took the first, second, and booster doses is presented in Table 1.

Table 1 Summary of the total vaccination based on gender and dosage

The total number of people vaccinated against COVID-19 is 436,598 with a daily average of 3898. 49.78% of the vaccinated people are male, while 50.22% are female. 76% took a single dose, 5.1% took a second shot, and 18.3% took a booster dose. Out of all those who took a single dose, 49.9% are male and 50.1% are female. Out of all those who took the second dose, 47.4% are male and 52.6% are female. Out of all those who took the booster dose, 49.8% are male and 50.2% are female.

Four t-tests were conducted to compare the means of the first, second, and booster doses between males and females. First, there are no significant mean differences between males and females for those who took the first and booster doses, respectively. Second, there are significant mean differences between males and females for those who took the second dose. Generally, there are no significant mean gender differences for those vaccinations.

Percentage Coverage and Coverage across the 23 LGAs

The percentage coverage (PC) is calculated using; $\:\text{P}\text{C}=\frac{Achieved\:vaccination}{\text{T}\text{a}\text{r}\text{g}\text{e}\text{t}\:\text{v}\text{a}\text{c}\text{c}\text{i}\text{n}\text{a}\text{t}\text{i}\text{o}\text{n}}\times\:100=\frac{436598}{432000}=101.06\%$

The percentage coverage is 101.06%. Further breakdown shows that the vaccination teams exceeded the target in 10 LGAs and did not reach the target in 13 LGAs (Fig. 1).

Fig. 1

Covid-19 Vaccination Coverage across the 23 LGA

The figure clearly shows the target against covered and is arranged in decreasing order of the difference between the achieved and targeted vaccination numbers of the 23 LGAs. Targets were exceeded in 10 out of the 23 LGAs. The highest vaccination was achieved in Mokwa LGA, while the lowest was in Mashegu LGA.

The t test (T = 0.117999497, p = 0.9071) showed that there are no significant mean differences between the targeted and achieved vaccinations despite differences in the number of targeted and achieved vaccinations across the 23 LGAs of the state.

The gender disaggregation of the vaccination across the LGAs is shown in Fig. 2.

More males than females were vaccinated in 12 LGAS. The LGAs are Mokwa, Bida, Chanchaga, Mariga, Borgu, Lapai, Agaie, Rijau, Bosso, Suleja, Magama, and Mashegu. On the other hand, more females than males were vaccinated in 11 LGAs. The LGAs are Lavun, Edati, Kontagora, Gurara, Tafa, Rafi, Paikoro, Shiroro, Agwara, Munya, and Wushishi.

Fig. 2

Gender Distribution of Covid-19 Vaccination Coverage across the 23 LGA

The T-test (T = -0.142798923, p = 0.8877) showed that there are no significant mean differences between the male and females that took the vaccinations across the 23 LGAs. The negative value indicates that males are less than females. The result is consistent with the earlier one that there are no significant mean differences in the gender of those who took the COVID-19 vaccine.

Dosage type across the 23 LGAs

The summary of the dose type administered across the 23 LGAs is presented in Table 2. Mokwa LGA recorded the highest, while Wushishi recorded the least first-dose vaccination. Gurara recorded the highest, while Edati, Kontagora, Mashegu, and Rijau recorded zero second-dose vaccinations. Borgu recorded the highest, while Magama and Rijau recorded 2 and 0 booster doses, respectively.

Table 2 Summary of the dosage type across the 23 LGAs

Integration of routine immunization

Routine immunization (RI) was integrated into COVID-19 vaccination, which is a double-edged knife strategy to ensure that essential vaccinations for other preventable diseases continue while addressing the COVID-19 pandemic. The team targeted women attending both ante-natal and post-natal at the PHCs in Niger State, Nigeria. The antigens administered are presented in Table 3. Out of the 80 teams that reported 4468 vaccination data times over the 16 weeks, 2735 (61.2%) did not integrate COVID-19 vaccination with RI, while 1733 (38.8%) did.

Four major RIs were integrated as presented in Table 3.

Table 3 Routine integration co-administered with COVID-19 vaccine

A total of 60,373 RI to children, especially zero-dose children who missed immunization due to disruptions caused by COVID-19. A breakdown showed that 17.6%, 18.3%, 17.6%, and 46.5% were given Penta, POV, IPV, and other vaccines, respectively, while the caregivers took the COVID-19 vaccine. For example, some parents received tetanus vaccines.

The total COVID-19 vaccinations were grouped into those that reported integration with RI and those that did not. 180,254 vaccinations, representing 41.3% of the total, were integrated with RI, while 256,344 vaccinations, representing 58.7%, were done without any integration (Table 4).

Table 4 Vaccinations done with and without integration disaggregated by gender

Out of the vaccinations done with integration, 48.9% were male and 51.1% were female. Out of the vaccinations done without integration, 50.4% were male and 49.6% were female. This is unsurprising, as women attending antenatal and postnatal services were targeted. Consequently, there is a significant mean difference between the males and females that took the COVID-19 vaccinations when integration of RI was adopted. More males than females were vaccinated when integration with RI was not adopted. Furthermore, the t-test result showed that there was a significant mean difference between the males and female who took COVID-19 vaccinations when integration with RI was not used.

Out of the 80 teams on the field that reported 4468 times on the dashboard (daily data upload) throughout the duration of the immunization, average vaccinations of 104 and 94 were reported by the teams that use integration with RI and those that do not, respectively, as shown in Table 5. The average vaccination is obtained by dividing the total vaccinations by the number of times reported, respectively, by the two groups.

Table 5 Average COVID-19 vaccinations by integration strategy

The average vaccination rate is higher where integration was done. Although fewer teams reported using integration, interestingly, they reported a higher mean than the other teams that did not incorporate integration with RI.

Discussion

The study corroborates an earlier study in Belize [14] that the integration of routine immunization (RI) into COVID-19 vaccination increases coverage but has no negative effect on the uptake of both COVID-19 vaccination and other routine immunization, which is necessary to address the disruption of RI caused by the COVID-19 pandemic, as a cohort study done in eight United States (US) health systems revealed [15]. Hence, combining COVID-19 vaccination with RI can be an effective and efficient strategy to achieve vaccination targets, build herd immunity, and improve public health.

The research has shown that a greater percentage took the first dose, while a few percentages took the second and booster doses, respectively. This is a great concern because, given the ever-increasing threats of the emergence of new COVID variants and concerns about waning immunity from the primary COVID-19 vaccines, second and booster shots emerged as a scientifically proven viable option to shore up protection against COVID-19 [16]. Hence, integration with RI led to an increase in coverage for those who took the first COVID vaccine dose, not necessarily booster doses. Strategies to shore up booster shots, reduce vaccine hesitancy, while integrating COVID-19 vaccination with RI are highly recommended to have effective control over the pandemic. Some strategies have been identified, such as dealing with misinformation, addressing political will, and some religious and cultural variables that fuel vaccine hesitancy [17].

The paper reported that there are no significant mean gender differences among those who took COVID-19 vaccinations, which suggests that there may not be a substantial gender-based disparity in either access to or acceptance of the vaccine among the study population. However, it is crucial to interpret this finding with extreme caution because several factors might be responsible for this result. Factors such as sample size, nature of the population, timing of the study, methodology used, vaccination model, cultural and social factors, and geographical considerations may be responsible, as may other latent or confounding variables that may be difficult to measure with precision.

Since gender was not considered in the computation of the target vaccination, attempts at addressing equity are taken through the strategies used for the vaccinations. In this case, it is important to check whether the integration with RI led to disparities between males and females. Data on gender was collected during the implementation phase of the research, and as such, no gender target was set from the onset. The study area is almost homogenous in religion and ethnicity and has similar geographic features and climatic conditions. Hence, this work does not completely confirm equity or a lack of gender disparities, but in the specific context and population studied, such disparities or inequities may not be pronounced. For example, this paper differs from a study conducted in Maharashtra State, India, that showed that gender disparities exist in COVID-19 vaccination [18]. A broader and more comprehensive study that incorporates different factors is highly recommended to determine the relevant factors that could cause disparities.

Another aspect of equity reported in this research is that there are no significant mean differences between the targeted and achieved vaccinations. This comes despite the differences in the number of targeted and achieved vaccinations across the 23 LGAs of the state. Technically, the differences in target and achieved are within the acceptable threshold, meaning that all targets were met with some allowable probabilities. The profound limitation here is that only geography equity is one aspect of a broader issue. Apart from gender and geography reported in this paper, other disparities may be considered in future research: age, socioeconomic status [19], ethnic affiliation [20], racial [21], infrastructure or health care systems, political ideology [22], health behaviors, social vulnerability [23], environmental, technological, and cold supply chain [24], and cultural factors. The geography can be local government areas (LGAs) as reported in this paper or rural versus urban as a study done in the US [25]. While the study reported disparities between rural and urban areas, this study reported no disparities across the 23 LGAs of Niger State, Nigeria.

Despite a smaller proportion of teams (38.8%) utilizing integrated COVID-19 vaccinations with Routine Immunization (RI), they accounted for a significant portion (41.3%) of the total vaccinations administered. Conversely, the majority of teams (61.2%) that did not integrate RI administered 58.7% of vaccinations. In addition, the team that used integration reported higher daily average vaccinations than the other team. This corroborates earlier studies that found integration improved vaccination coverage [26–27]. Integration has also helped to target especially zero-dose children in the rural areas of the study area, which is an attempt to address disruptions of RI caused by the COVID-19 pandemic [28] and inequities in infant and adult RI and COVID-19 vaccination completion between the urban and rural areas of Nigeria [29].

More females were vaccinated when integration was reported, and there was a significant mean gender difference in COVID-19 vaccinations when integration of RI was adopted. Equities were distorted because integration was targeted at children and women attending antenatal and postnatal services at PHC in Niger State, Nigeria. Interestingly, RI has helped to reduce vaccine hesitancy among females, according to a study in Kenya that found that COVID-19 vaccine hesitancy is higher in females than males [30]. On the other hand, more males were vaccinated when integration was not used, and there is a significant mean gender difference in COVID-19 vaccinations when integration with RI was not used. Two possible explanations can be made. First, females are most likely to gravitate toward PHCs with the prospect of RI because of antenatal and postnatal services. Secondly, it would be most likely to obtain samples that contain more males than females since the Niger state population consists of more males than females [31].

The Health Equity Framework [32] provides a valuable lens for analyzing the study’s findings, emphasizing the need to address disparities in health outcomes and access to healthcare. The study shows that integrating RI into COVID-19 vaccination efforts significantly increased vaccine coverage, particularly benefiting zero-dose children and women attending antenatal and postnatal services. However, it also revealed gender disparities, as more females received vaccinations when RI was integrated, highlighting the need for gender-specific strategies to ensure equitable access for males. While geographic equity in vaccine distribution was observed across the 23 LGAs, the framework suggests further investigation into disparities within urban and rural areas. Additionally, the integration of RI helped mitigate immunization gaps caused by the pandemic, but broader equity dimensions, such as socioeconomic status and ethnicity, require further exploration to ensure comprehensive healthcare access.

The study has several strengths, including its comprehensive data analysis, which provides a detailed breakdown of vaccination coverage by gender and geography, offering valuable insights into equity issues. It effectively demonstrates the benefits of integrating routine immunization (RI) with COVID-19 vaccination, presenting a practical strategy for improving vaccine coverage in resource-limited settings. By specifically targeting zero-dose children, the study addresses a critical gap in routine immunization, contributing to broader public health efforts. Additionally, the findings are based on real-world data from a large-scale vaccination campaign, enhancing their relevance for policymakers and public health practitioners seeking to design effective immunization strategies. On the other hand, the study has several limitations, including a limited scope of equity analysis, as it primarily focuses on gender and geographic disparities without exploring other critical factors such as socioeconomic status, ethnicity, or urban-rural differences. Additionally, it lacks data on marginalized and hard-to-reach populations, restricting its ability to fully assess equity concerns. The study also does not account for potential confounding factors, such as cultural, religious, or political influences, which could impact vaccine uptake and equity. Furthermore, its short-term focus, covering only April to July 2023, may not capture long-term trends or the sustainability of the integration strategy. A key limitation is the absence of data on urban and rural locations, as well as marginalized populations, which could have provided a more comprehensive understanding of inequities in vaccine access.

Policy recommendations

Given the routinization of COVID-19 vaccination in Nigeria, policymakers should formally adopt integrated vaccination models that combine RI with COVID-19 vaccination to improve coverage, reduce operational costs, and enhance disaster preparedness. This approach should be embedded in future pandemic response plans to ensure the continuity of essential vaccinations during emergencies. Integration has proven effective in reducing the zero-dose burden, particularly among marginalized populations, and should be expanded using mobile teams and community outreach. Equity-focused vaccination policies must address gender, geographic, and socioeconomic disparities, while incentives like cash transfers and community rewards can boost booster dose uptake. Strengthening data collection and monitoring, investing in public awareness campaigns, and expanding access to hard-to-reach populations are crucial for sustained progress. Gender-inclusive strategies should be integrated into national immunization programs, and long-term investments in healthcare infrastructure and workforce training are necessary for sustainability. Further research on integration’s impact on vaccine equity is essential, alongside international collaboration to secure funding and technical support for scaling up integrated vaccination efforts.

Conclusion

In line with the Federal Government of Nigeria’s commitment to vaccinating all 111,776,503 eligible Nigerians with COVID-19 vaccines, this study demonstrates that integrating RI into COVID-19 vaccination programs is a viable and effective strategy to increase vaccine coverage, reduce the zero-dose burden, and strengthen public health systems. The findings reveal that integration significantly improved first-dose COVID-19 vaccine coverage, particularly among zero-dose children and women attending antenatal and postnatal services. However, the uptake of second and booster doses remained low, underscoring the need for targeted strategies to promote complete vaccination series and address vaccine hesitancy. While no significant gender or geographic disparities were observed in COVID-19 vaccine coverage, the integration of RI introduced potential inequities, as a higher proportion of females received routine immunizations compared to males. This highlights the importance of designing gender-sensitive strategies to ensure equitable access for all populations. Additionally, the study emphasizes the need to consider other dimensions of equity, such as age, socioeconomic status, ethnic affiliation, and infrastructure, in future vaccination programs. The integration of RI with COVID-19 vaccination not only addresses immediate immunization gaps but also serves as a model for future pandemic preparedness. By leveraging this approach, policymakers can ensure the continuity of essential vaccinations during health emergencies, reduce the zero-dose burden, and build resilient health systems capable of responding to future crises. However, further research is needed to explore the long-term impact of integration on vaccine equity, particularly among marginalized and hard-to-reach populations, and to identify strategies for sustaining these gains. In conclusion, integrating RI into COVID-19 vaccination is a practical and efficient strategy to improve vaccine coverage, reduce disparities, and enhance disaster preparedness. Policymakers should adopt this approach as a national strategy, ensuring that it is tailored to address the unique needs of different subpopulations and supported by robust data collection, community engagement, and equitable resource allocation. By doing so, Nigeria can achieve its vaccination targets, strengthen its health systems, and safeguard public health for all.