High-Resolution Geospatial Mapping of Zero-Dose and Underimmunized Children Following Nigeria's 2021 Multiple Indicator Cluster Survey/National Immunization Coverage Survey.

BACKGROUND: "Zero-dose" children are those who are without any routine vaccination or are lacking the first dose of the diphtheria, tetanus, and pertussis-containing vaccine. Based on global estimates from the World Health Organization/United Nations Children's Fund in 2022, Nigeria has the highest number of zero-dose children, with >2.3 million unvaccinated. METHODS: We used data from the 2021 Nigeria Multiple Indicator Cluster Survey/National Immunization Coverage Survey to identify zero-dose and underimmunized children. Geospatial modeling techniques were employed to determine the prevalence of zero-dose children and predict risk areas with underimmunized children at a high resolution (1 × 1 km). RESULTS: Zero-dose and underimmunized children are more prevalent in socially deprived groups. Univariate and multivariate bayesian analyses showed positive correlations between the prevalence of zero-dose and underimmunized children and factors such as stunting, contraceptive prevalence, and literacy. The prevalence of zero-dose and underimmunized children varies significantly by region and ethnicity, with higher rates observed in the country's northern parts. Significant heterogeneity in the distribution of undervaccinated children was observed. CONCLUSIONS: Nigeria needs to enhance its immunization system and coverage. Geospatial modeling can help deliver vaccines effectively to underserved communities. By adopting this approach, countries can ensure equitable vaccine access and contribute to global vaccination objectives.

High-resolution geospatial mapping of zero-dose and under-immunized children following Nigeria's 2021 multiple indicator cluster survey/national immunization coverage survey (MICS/NICS).

BACKGROUND: The "zero-dose" children are those without any routine vaccination or lacking the first dose of the diphtheria-tetanus-pertussis-containing vaccine. As per 2022 WHO/UNICEF estimates, globally, Nigeria has the highest number of zero-dose with over 2.3 million unvaccinated. METHODS: We used data from the 2021 Nigeria Multiple Indicator Cluster Survey - National Immunisation Coverage Survey to identify zero-dose and under-immunized children. Geospatial modelling techniques were employed to determine the prevalence of zero-dose children and predict risk areas with under-immunized at a high resolution of 1x1 km. RESULTS: Both zero-dose and under-immunized children are more prevalent in socially deprived groups. Univariate and multivariate Bayesian analyses showed positive correlations between the prevalence of zero-dose and under-immunized children with factors like stunting, contraceptive prevalence, and literacy. The prevalence of zero-dose and under-immunized children varies significantly by region and ethnicity, with higher rates observed in the country's northern parts. Significant heterogeneity in the distribution of under-vaccinated children was observed. CONCLUSIONS: Nigeria needs to enhance its immunization system and coverage. Geospatial modelling can help deliver vaccines effectively to underserved communities. By adopting this approach, countries can ensure equitable vaccine access and contribute to global vaccination objectives.