Introduction: Identifying actionable targets is crucial to improve overall and equity in vaccination coverage, and in line with the global Immunization Agenda 2030. Therefore, this study seeks to assess the prevalence of missed opportunities for simultaneous vaccination (MOSVs) and their impact on vaccination coverage and urban-rural inequity in The Gambia.
Methods: We used data of children aged 12-23 months from The Gambia 2019/2020 demographic and health survey (weighted n = 1355) with seen vaccination cards. We analyzed: the frequency of MOSVs; percentage point coverage reduction attributable to MOSVs for 18 vaccine doses and full basic vaccination; and MOSVs' contribution to urban-rural coverage inequity through Blinder-Oaxaca decomposition.
Results: Sixty percent of children experienced MOSVs, in both urban and rural areas, but urban MOSVs were more seldom corrected (35.9 % vs 45.3 %). All eighteen vaccine doses assessed could have achieved between one to eleven percentage points higher coverage if MOSVs had been avoided, with full basic vaccination gaining even more. While MOSV correction did not impact overall urban-rural coverage inequity, it did exacerbate (explained coefficient = -0.1007; P = 0.002) inequities among children who experienced MOSVs, explaining 95 % of the observed difference.
Conclusion: Our study highlights the prevalence and negative impact of MOSVs on overall vaccination coverage. Although MOSVs did not contribute significantly to the total urban-rural inequity in coverage, they have detrimental effects on vaccination coverage and urban-rural inequity among children who had experienced MOSVs. Addressing MOSVs, can enhance coverage and reduce the risk of under-vaccination, aligning with global initiatives.