Yellow Fever Outbreaks and Reactive Vaccination in Africa, 2010-2025: A Scoping Review and Analysis.

Containing yellow fever (YF) outbreaks rapidly through reactive vaccination campaigns (RVCs) is a key objective of the 2017-2026 Eliminate Yellow Fever Epidemics (EYE) strategy. We conducted a scoping review and quantitative analysis using grey and peer-reviewed literature on YF outbreaks in Africa (2010-2025) to compare how factors including outbreak size and timing of RVCs have changed pre- and post-EYE strategy. The overall median time between YF index case and RVC was 90.5 days (interquartile range [IQR]: 53.8-113.2), with medians of 108 days (IQR 59-111) for 2010-2016 and 79 days (IQR 51-114.5) for 2017-2025. The median (IQR) reported cases per outbreak was 91 (IQR: 16-276) in 2010-2016 and 94 (49-377) in 2017-2025, with case fatality ratios (CFRs) of 8.5% (standard error [SE]: 2.1%) and 4.9% (SE: 2.9%), respectively. High morbidity and mortality for YF persist in Africa, and more timely RVCs will be required to achieve YF control.