Effectiveness of monitoring mechanisms in reducing immunization dropouts among infants in health facilities of Maridi County, South Sudan.

Abstract

Childhood immunization is among the most cost-effective public health strategies available, yet dropout rates, the proportion of infants who begin but fail to complete the recommended vaccination schedule, remain a persistent obstacle to achieving high and equitable coverage. Global third-dose pentavalent coverage stood at 86% in 2019, declined to 84% in 2020, and fell further to 82% in 2021, consistently falling short of the 85% minimum target. This shortfall is especially pronounced in fragile health systems such as that of South Sudan, where facility-level and community-level monitoring mechanisms vary widely in availability and quality. I conducted a prospective cohort study from 1 October to 31 December 2023 in Maridi County, Western Equatoria State, South Sudan. Fourteen health facilities were selected by stratified random sampling (seven from payams with active Boma Health Initiative [BHI] activities and seven from payams without). One vaccinator per facility was selected by coin toss, yielding 26 participants. A semi-structured interview guide administered in month one and a monthly observation checklist applied across all three months were used to collect data. Data were analyzed using descriptive statistics, chi-square tests, Spearman correlations, and multivariable regression to assess associations between monitoring mechanisms and facility-level dropout rates. Three of the 14 facilities (21%) had no monitoring chart; 28.6% recorded a dropout rate above 10%, while half (50%) achieved the target of below 10%. Facilities with updated monitoring charts were significantly less likely to record high dropout rates (Spearman r = -0.725, p = 0.003). Boma Health Workers (BHWs), community-level health personnel who mobilize, trace, and refer immunization defaulters, were attached to 64% of facilities; 91.7% of facility-months in the low-dropout category had BHWs present, compared with 37.5% in the high-dropout category. Over the three months of observation, the proportion of facilities recording a dropout rate above 10% fell by 9.6 percentage points. Facility-based monitoring tools used by health workers (monitoring charts, immunization registers, and defaulter tracing systems) and community-based monitoring carried out by BHWs were each independently associated with lower dropout rates, and their combination appears to have a complementary effect. Neither mechanism was sufficient alone. We recommend that health workers use monitoring tools consistently and that the Boma Health Initiative be scaled up to health facilities currently without BHWs.