Five decades of progress in vaccine-preventable disease surveillance and immunization coverage in East and Southern Africa: focus on polio and measles

This is the authors' abstract. We don't add key points for this paper.

Introduction: over the past fifty-years, the East and Southern Africa sub region has made significant progress in vaccine-preventable disease (VPD) surveillance, particularly for polio and measles. The establishment of WHO's Expanded Programme on Immunization in 1974 laid the groundwork for strong surveillance systems, with polio and measles surveillance evolving through targeted initiatives and improved methodologies. These efforts strengthened infrastructure and enhanced readiness for emerging infectious diseases. Methods: we conducted a mixed-methods secondary analysis using data from 20 ESA countries (1980-2024), sourced from WHO databases, joint reporting forms and program reviews. The study traced the evolution of VPD surveillance systems, highlighting a shift from passive reporting to active case finding and indicators for vaccination coverage and VPD surveillance. Results: between 1980 and 2024, East and Southern Africa (ESA) countries reported millions of measles, polio, rubella, diphtheria, pertussis, and neonatal tetanus cases, with notable declines followed by resurgences. Surveillance improvements, supported by WHO, revealed shifting disease patterns and emphasized the need for continued investment in immunization, laboratory capacity, and outbreak response. Acute Flaccid Paralysis (AFP) surveillance quality improved, with stool adequacy rising from 46% in 2000 to 91% in 2015. Routine vaccination coverage peaked between 2010 and 2019. From 2016 to 2024, measles and rubella IgM testing showed increased positivity and workload, especially post-COVID. Conclusion: the ESA subregion has made significant strides in VPD surveillance and immunization coverage. However, recent resurgences reveal gaps to be addressed. Maintaining investment in surveillance systems, laboratory capacity, and routine immunization, especially in underperforming countries is essential for timely detection, investigation, response, and recovery from outbreaks.