Closing immunization gap: Complete basic childhood vaccination and associated factors among children aged 12–23 months in Tanzania; a multilevel analysis of the 2022 Demographic and Health Survey

Vaccination prevents an estimated 4-5 million deaths globally each year, including many among children under five. However, complete childhood vaccination coverage remains low in Sub-Saharan Africa, including Tanzania. This study examined complete basic vaccination coverage and associated factors among Tanzanian children aged 12-23 months. Analytical cross-sectional study of the 2022 Tanzania Demographic and Health Survey data was conducted. The sampling frame was stratified by geographic region and urban/rural areas, using a two-stage sampling method that selected primary sampling units based on census enumeration areas, followed by household selection using probability systematic sampling. Multilevel logistic regression, accounting for the complex survey design, was used to identify individual and community-level factors associated with complete childhood vaccination. Adjusted odds ratios (OR) and 95% Confidence intervals (CI) were used to estimate the strength of association. The prevalence of complete basic childhood vaccination was 52.5% (95%CI: 49.6 -55.3). Among these children, coverage for individual vaccines was high, with 86.5% receiving the first dose of measles and 91.0% receiving (Bacillus Calmette-Guérin) BCG. However, the percentage receiving the full dose was lower for polio (58.9%) and 90.0% for Diphtheria, Pertussis, and Tetanus (DPT). Mothers with primary, secondary/higher education, in middle wealth quintile, had more than four antenatal care (ANC) visits, had 1-2 under-five children had lower odds to completely vaccinate their children. At the community level, mothers in western, central zones and Zanzibar had higher odds to vaccinate their children. Complete basic childhood vaccination coverage in Tanzania was suboptimal and associated with various factors including maternal education, middle wealth, more ANC visits, and fewer young children exhibited higher odds of vaccination. Western, central zones, and Zanzibar showed higher coverage. Targeted interventions addressing education, wealth, ANC, family size, and regional disparities would be crucial to improve vaccination rates in Tanzania.