Morbidity and mortality burden of seasonal influenza in sub-Saharan Africa: a systematic review and meta-analysis protocol

Seasonal influenza poses a significant global health burden, responsible for substantial morbidity and mortality annually, particularly among high-risk populations such as the elderly, young children, pregnant women, and individuals with chronic illnesses. While the burden of influenza is well-documented in high-income countries, limited data exist for sub-Saharan African (SSA) countries, where fragile healthcare systems and underreporting obscure the true impact. Influenza exacerbates prevalent health conditions such as HIV, malaria, and malnutrition, further increasing its toll. The meta-analysis outlined in this protocol aims to systematically assess the morbidity and mortality burden of seasonal influenza in SSA countries, providing policymakers with critical insights to strengthen surveillance, prioritize at-risk populations, and inform vaccination strategies. This is a protocol for a planned systematic review and meta-analysis. This research will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines, incorporating observational studies and surveillance reports published between August 2010 and December 2026. We will search major health databases, including MEDLINE (via PubMed), Embase, Scopus, Web of Science, and the Cochrane Library, as well as regional databases (African Index Medicus and the WHO Global Index Medicus) and grey literature sources (medRxiv and national health reports). Studies reporting laboratory-confirmed seasonal influenza cases from SSA countries will be included. A standardized form will be used for data extraction, capturing morbidity (prevalence, incidence, and hospitalization rates) and mortality (case-fatality rates and excess mortality rates) indicators. Pooled data will be analyzed using meta-analytic techniques, applying random-effects models to account for heterogeneity. Sensitivity analyses will address variations in case definitions, methodologies, and study quality across studies. Publication and language bias will be mitigated by including grey literature and applying no language restrictions. The completed review is expected to provide updated, pooled estimates of seasonal influenza-associated morbidity and mortality across SSA countries, stratified by age group, geographic subregion, and presence of comorbidities. These findings will support evidence-based policy decisions, including the strengthening of influenza surveillance systems and the prioritization of vaccination programs for high-risk populations in SSA countries. As this study involves secondary data from published literature, ethical approval is not required. Results will be disseminated via a peer-reviewed publication, conference presentations, and stakeholder meetings. Tailored reports will be shared with policymakers in SSA countries to translate findings into public health strategies, particularly to enhance surveillance and implement targeted vaccination programs. PROSPERO CRD42024617707