Measles vaccine effectiveness in African children: a systematic review and meta-analysis

Introduction: Measles is an extremely contagious viral disease that can be prevented through vaccination. It is caused by the measles virus and presents with symptoms such as high fever, cough, runny nose, conjunctivitis, and a distinctive rash. Complications may include pneumonia, diarrhoea, and neurological issues. The disease spreads through respiratory droplets and continues to pose a significant public health challenge, especially in Africa, despite vaccination efforts. Objective: This systematic review and meta-analysis aim to estimate the pooled vaccine effectiveness of measles vaccines among African children, providing insights into immunization program success and informing policy decisions on vaccine distribution and resource allocation. Methods: Following PRISMA guidelines, search was conducted in databases including PubMed/Medline, Science Direct, HINARI, Cochrane/Wiley library, Europe PMC, and grey literatures like Google Scholar up to March 2024. Cross-sectional studies assessed measles vaccine effectiveness in African children aged nine months and above were included. Data was extracted using JBI extraction tool and entered into microsoft excel and analysed via STATA version 20.1 using random effect model. Results: From 5295 identified articles, 18 met the inclusion criteria, encompassing 26,470 children from 13 African countries. The pooled measles vaccine effectiveness was 68.58%, with significant heterogeneity (I2 = 99.66%, p < 0.001). Subgroup analysis showed variability in vaccine effectiveness by study period, with higher effectiveness in studies conducted after the Global Vaccine Action Plan (GVAP) in 2012. Conclusion: Measles vaccine effectiveness varies in African regions, ranging from 98.4% in Nigeria to 36.5% in Mozambique, with an overall effectiveness of 68.58% and high heterogeneity among studies. Optimizing vaccine distribution, increasing coverage, and prompt administration are important for enhancing effectiveness. Continued support for GVAP strategies and further research is needed to understand factors affecting vaccine performance and improve immunization efforts in Africa.