A yellow fever outbreak in Colombia is behaving in ways that have alarmed global health officials — with a case fatality rate that in several reporting periods has exceeded 40 to 70 percent, far above the typical 10 to 30 percent historical mortality rate for this viral hemorrhagic fever. Since the outbreak began in late 2024, a total of 168 confirmed cases and 76 deaths have been reported across Colombia, spanning at least 10 departments including Tolima, Caldas, Caquetá, Cauca, Guaviare, Huila, Meta, Nariño, Putumayo, and Vaupés. In 2026 alone, 35 confirmed cases and 18 deaths were reported through early April.
The Department of Tolima has become the epicenter — historically a low-risk zone that had not experienced significant yellow fever activity in the modern vaccination era. Colombia administered nearly 5 million yellow fever vaccine doses between September 2024 and January 2026, but persistent gaps in adult vaccination coverage — particularly among rural workers and communities that expanded into previously forested areas where the Aedes and Haemagogus mosquito vectors are present — continue to drive cases.
