Effects of Good Practices for Catch-Up Vaccinations: Assessment with a Quasi-Experimental Study in Democratic Republic of Congo

Introduction: Despite the enormous resources deployed and the success achieved in vaccination, reducing the number of children who remain unvaccinated remains a major operational challenge in certain countries. In 2014, the Kalemie Expanded Program of Immunization outpost in the Democratic Republic of the Congo was faced with a high number of unvaccinated children. They instituted a “token” catch-up system based on a collaborative approach with community health workers. This study aims to document the effects of this strategy on vaccination coverage. Methods: This study was a comparative quasi-experimental test/control study. The “test” health area was Undugu where the catch-up strategy was implemented and the “control” health area was Kanunka. A vaccination coverage survey was conducted according to the WHO method in both health areas, examining children aged 12 to 23 months. The proportions were compared using a Pearson chi-square test and the odds ratios were estimated. Results: Vaccine coverage was significantly higher in the “test” health area for all the antigens. Full vaccination coverage was 69.4% in the “test” health area versus 31% in the “control” health area, with a 4.7 times greater chance of being fully vaccinated in the “test” health area (OR: 4.7; CI 95% [3.1 - 7.2]; p = 0.0001). Conclusion: This study demonstrates the value of a strategy that can increase access to vaccination and use of vaccination services, leading to a reduction in inequality in this area. However, this is linked to adapting the collaborative model on which it is based. This must be taken into consideration in plans to reproduce the findings.