Geospatial variations in the prevalence of children missing out of diphtheria-pertussis-tetanus vaccination in Nigeria: estimates from multiple household surveys

BACKGROUND: Vaccination remains one of the most effective public health measures, yet many children in Nigeria continue to miss essential vaccines, leaving them exposed to preventable diseases. Understanding the geographic and temporal patterns of missed vaccinations is important for designing targeted and equitable immunization strategies. This study investigates the geospatial variations in the prevalence of children who missed diphtheria-pertussis-tetanus vaccination in Nigeria. METHODS: Data were obtained from the Nigeria Demographic and Health Surveys conducted between 2003 and 2023/2024. Bayesian geostatistical models were fitted within the Integrated Nested Laplace Approximation (INLA) framework to estimate the prevalence of zero-dose and under-immunized children across states and survey periods. Exceedance probability maps were used to identify states with a high likelihood that the prevalence of zero-dose children exceeded ten percent. RESULTS: The results show clear geographic clustering, with persistently higher prevalence of missed vaccinations in the northern regions compared to the south. Dropout between consecutive DPT doses has decreased over time, indicating improved follow-through once children start vaccination; however, each successive dose still shows a higher prevalence of missed vaccinations than the preceding one. Exceedance probability maps further highlight states such as Kebbi, Sokoto, Zamfara, and parts of Niger, Kwara, Borno, Yobe, Taraba, and Kogi, where the likelihood of zero-dose prevalence surpassing 10% remains high. CONCLUSION: Despite improvements in childhood vaccination coverage, large geographic disparities persist, especially in northern states. The continued presence of states with a high probability of zero-dose prevalence suggests that national progress has not resulted in equitable gains. Strengthening local immunization systems, addressing regional barriers, and prioritizing targeted interventions are needed to ensure that all children benefit from routine vaccination services.