Impact of health system strengthening on delivery strategies to improve child immunization coverage and inequalities in rural Madagascar

To reach global immunization goals, national programs need to balance routine immunization at health facilities with vaccination campaigns and other outreach activities (e.g. vaccination weeks), which boost coverage at particular times and help reduce geographic inequalities. However, where routine immunization is weak, an overreliance on vaccination campaigns may lead to heterogeneous coverage. Here, we assessed the impact of a health system strengthening (HSS) intervention on the relative contribution of routine immunization and outreach activities to reach immunization goals in rural Madagascar.We obtained data from health centers in Ifanadiana district on the monthly number of recommended vaccines (BCG, measles, DTP and Polio) delivered to children, during 2014-2018. We also analyzed data from a district-representative cohort carried out every two years in over 1500 households in 2014-2018. We compared changes inside and outside the HSS catchment in the delivery of recommended vaccines, population-level vaccination coverage, geographic and economic inequalities in coverage, and timeliness of vaccination. The impact of HSS was quantified via mixed-effects logistic regressions. The HSS intervention was associated with a significant increase in immunization rates (Odds Ratio between 1.22 for measles and 1.49 for DTP), which diminished over time. Outreach activities were associated with a doubling in immunization rates, but their effect was smaller in the HSS catchment. Analysis of cohort data revealed that HSS was associated with higher vaccination coverage (Odds Ratio between 1.18 per year of HSS for measles and 1.43 for BCG), a reduction in economic inequality, and a higher proportion of timely vaccinations. Yet, the lower contribution of outreach activities in the HSS catchment was associated with persistent inequalities in geographic coverage, which prevented achieving international coverage targets. Investment in stronger primary care systems can improve vaccination coverage, reduce inequalities and improve the timeliness of vaccination via increases in routine immunizations. Key questionsO_ST_ABSWhat is already known?C_ST_ABS- Reaching the minimum recommended vaccination coverage of 90% for childhood illnesses remains a substantial challenge for low and middle income countries (LMICs). - Understanding how vaccine delivery strategies can be improved to achieve coverage targets in rural areas of LMICs is essential due to the fragility of health systems and associated health budgets. - While evidence exists on the impact of outreach activities and other targeted interventions aimed at improving immunization coverage, it is unclear how strengthening local health systems can help improve key indicators of vaccination coverage, via its different impacts on routine and outreach immunizations. What are the new findings?- A health systems strengthening (HSS) intervention in a rural district of Madagascar improved overall vaccination coverage, reduced economic inequalities in vaccination coverage, and increased the proportion of timely vaccinations via an increase in routine immunizations. - The contribution of outreach activities was lower in the HSS catchment area than in the rest of the district, which was associated with a persistence of geographic inequalities in vaccination coverage. What do the new findings imply?- Strengthening local health systems can help improve key indicators of vaccination coverage in rural, low resource settings, even when those interventions do not target specifically vaccine improvements themselves. - Explicit efforts are still necessary in areas undergoing HSS to vaccinate children in remote areas so that immunization goals can be reached.