Timeliness and completeness of vaccination and risk factors for low and late vaccine uptake in young children living in rural southern Tanzania

Background: We studied coverage and timeliness of vaccination and risk factors for low and delayed vaccine uptake in children aged ,2 years in rural Tanzania.Methods: We used data from a cluster survey conducted in 2004, which included 1403 children. Risk factors were analysed by log-binomial regression adjusted for the clustering. The analysis was restricted to BCG, first and third dose of Diphtheria-Tetanus-Pertussis vaccines (DTP-1 and DTP-3) and first dose of measles-containingvaccine (MCV-1).Results: Coverage for BCG, DTP-1, DTP-3 and MCV-1 was 94%, 96%, 90% and 86%, respectively. Delayed vaccination (.1 month after the recommended age) occurred in 398/1205 (33%) children for BCG, 404/1189 (34%) for DTP-1, 683/990 (69%) for DTP-3 and 296/643 (46%) for MCV-1. Coverage was lower for all vaccines except DTP-1 in children living .5 km from a healthcare facility. Delayed uptake was associated with poverty. Low and delayed MCV-1 vaccination was associated with low maternal education. Delayed BCG vaccination was associated with ethnicity and rainy season.Conclusion: Despite reasonably high vaccination coverage, we observed substantial vaccination delays, particularly for DTP-3 and MCV-1. We found specific factors associated with low and/or delayed vaccine uptake. These findings can help to improve strategies to reach children who remain inadequately protected.