Background Despite the success and cost-effectiveness of immunisation in preventing infectious diseases, vaccine preventable diseases still contribute to child mortality in Africa. Results from the Nigeria Demographic and Health Survey suggest a low coverage of childhood immunisation reporting only 31% of Nigerian children who have received all basic vaccinations. This study aimed to determine the immunisation status of children under five, and significantly associated correlates regarding childhood immunisation and timeliness of vaccine uptake among these children in Badagry Local Government Area (LGA), Lagos, Nigeria.

Methods This descriptive cross-sectional study was conducted among 140 mothers of children under five residing in Badagry LGA, selected using multi-stage sampling. The main outcome was the child’s immunisation status. Data was collected using KoBoToolbox and sought information about immunisation history and associated independent variables of parental age, educational level, occupation, household characteristics, antenatal and birth history. Analysis was done with Epi Info ver 7. Associations between independent and dependent variables were assessed using chi square test with level of significance set at p<0.05. Ethical approval was obtained from Lagos University Teaching Hospital Human Research Ethics Committee (LUTH-HREC).

Results Majority (78.57%) of children were fully immunised in a timely manner, 7.86% were fully immunised in an untimely manner, 10.71% were incompletely immunised for age and only 4 children were unvaccinated. Although aware of childhood immunisation, 63.57% of them had poor knowledge regarding childhood immunisation. Statistically significant associations were found between a child’s immunisation status and maternal age (p=0.0072), mother’s highest educational level (p=0.0000), her husband’s age (p=0.0001) and highest educational level (p=0.0000), estimated household monthly income (p=0.0292), number of siblings a child had (p=0.0001), child’s place of birth (p=0.0000), antenatal care (p=0.0000) and vaccination card availability (p=0.0000).

Conclusion Badagry LGA is a major border town with heavy cross-border traffic facilitating transmission of diseases internationally. The gaps in immunization status of the children can be attributed to most mothers having poor overall knowledge. Parental age, educational level, estimated household income and household composition have significant impact on immunisation coverage and significantly, all unvaccinated children belonged to mothers with poor overall knowledge. Major limitations to this study were language barrier and unwillingness of mothers to be interviewed. This study demonstrates the need for continuous community engagement to improve immunisation completeness and timeliness of vaccine uptake.