Routine Childhood Immunization Coverage, Vaccination Dropout, and Predictors of Schedule Completion in Benin City, Nigeria

Abstract

High initial access to childhood vaccination does not guarantee schedule completion. This study assessed antigen-specific coverage, dropout, and factors associated with completion among children in Benin City, Nigeria. A community-based cross-sectional survey included 620 mother-child pairs selected through two-stage cluster sampling. Vaccination status was determined from records and maternal recall. Coverage and individual-level dropout were estimated, and two forced-entry multivariable logistic regression models examined completion by 12 months and extended-schedule completion by 15 months. Estimates were not adjusted for survey clustering or sampling weights. Coverage was 95.8% (594/620) for bacille Calmette-Guerin and 92.1% (571/620) for pentavalent dose three. Full-schedule coverage by 12 months was 76.8% (476/620). Among 460 children aged 15-23 months, 82.2% (378/460) received measles-containing vaccine dose two and 75.4% (347/460) completed the extended schedule. Dropout was 2.9% (17/587) from pentavalent dose one to dose three and 9.7% (40/414) from measles-containing vaccine dose one to dose two among age-eligible initial-dose recipients. Antenatal-care attendance was associated with higher odds of 12-month completion (adjusted odds ratio [AOR]=4.26, 95% confidence interval [CI] 2.20-8.26) and extended completion (AOR=3.48, 95% CI 1.62-7.49). Income of at least N60,000 was associated with 12-month completion, while Ikpoba-Okha residence was associated with lower extended completion.Completion declined for later doses. The associations support evaluating antenatal counselling, reminder-recall systems, and geographically targeted follow-up in prospective or implementation studies.