The Potential Contribution of Supplementary Immunization Activities to Routine Immunization in Kebbi State, Nigeria

Background: Among the strategies of the Polio Eradication Initiative, the landmark interventions are routine immunization (RI) and supplementary immunization activities (SIAs). RI is the provision of vaccination service at the health facility and conducted year-round. SIAs are a community-based intervention targeting large numbers of an eligible population within a short period. Hence, the study aimed to assess the contributions of SIAs on access and utilization of RI services. Methods: We conducted the study in 10 local government areas in Kebbi State, northwestern Nigeria. We analyzed RI data from January to September 2019 and included the 4 SIAs conducted in January, April, August, and September in the same years. The number of children vaccinated, the trend of BCG, pentavalent vaccine at 6 and 10 weeks, and measles coverage and dropout rates (DORs) were analyzed. Results: For all the selected vaccines, the highest contributions to RI were recorded during the August 2019 fractional Inactivated Polio Vaccine (fIPV) campaign. On the other hand, the least contributions were noted during January SIAs. The BCG coverage showed an erratic trend with the lowest in February and highest in July 2019. The coverage for the pentavalent vaccine at 6 and 10 weeks was lowest in February and September. The pentavalent vaccine DOR pattern showed the lowest in February with value of 0% and the highest in June with 12%. Except for May and June, the Pentavalent vaccine DORs for all other months were