Full immunization coverage, timeliness and dropout rates among children aged 12–59 months: a community-based cross-sectional study in a rural subnational district in Nigeria

Immunization is a cost-effective strategy to reduce morbidity and mortality associated with vaccine preventable diseases. To understand the drivers of reported gaps in vaccination coverage in rural areas, we examined full immunization coverage and its predictors, as well as vaccination timeliness and dropout rates in children aged 12–59 months in rural communities in a local district in Nigeria. This was an interviewer-administered cross-sectional study involving 1700 children aged 12 to 59 months selected by multistage sampling method from 22 communities. Immunization cards were inspected to ascertain each child’s immunization status. The primary analysis used a two-level mixed-effects logistic regression model, with children nested within communities. Ward-level clustering and ordinary binary logistic regression were assessed as sensitivity analyses. Adjusted odds ratios and 95% confidence intervals were reported. More than half of the recruited children were aged 12 to 23 months 867 (51.0%) and female 872 (51.3%). Full immunization coverage was 47.4%, and timeliness varied by type of vaccine, ranging from 40.8% in HBV0 to 65.2% in OPV1. Dropout rate for BCG to measles was 16.1%, Penta1 to Penta3 was 10.3% and Penta1 to measles was 16.5%. Upper socioeconomic status (AOR: 1.81; 95% CI: 1.21 – 2.70), increasing family income (AOR: 1.06; 95% CI: 1.00 – 1.11), delivery by healthcare professional (AOR: 1.7; 95% CI: 1.085-2.621), attending postnatal care (AOR: 1.72; 95% CI: 1.28 - 2.31) and reported convenience with time of immunization (AOR: 1.82; 95% CI: 1.33 - 2.50) increased the odds of full immunization, while increasing child age (AOR: 0.98; 95% CI: 0.98-0.99), living more than 2km of a facility (AOR: 0.66; 95% CI: 0.47-0.94), ever missing vaccination because of no vaccine (AOR: 0.31; 95% CI: 0.15 - 0.65) or vaccinator (AOR: 0.20; 95% CI: 0.06 - 0.69) reduced the odds. Full immunization coverage and vaccination timeliness among children aged 12 to 59 months included in the study was low, with high dropout rates recorded. Strengthening vaccine supply chain, ensuring health worker availability in facilities, encouraging delivery by professionals, and reinforcing caregiver counselling after delivery could contribute to improved full immunization coverage in rural communities.