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

We studied coverage and timeliness of vaccination and risk factors for low and delayed vaccine uptake in children aged 2 years in rural Tanzania. 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 DiphtheriaTetanusPertussis vaccines (DTP-1 and DTP-3) and first dose of measles-containing vaccine (MCV-1). 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 5km 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. 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.