Since the start of 2023 until February 25, 2024, a total of 13 countries in the WHO African Region have reported probable and confirmed cases of yellow fever (YF). These countries include Burkina Faso, Cameroon, the Central African Republic, Chad, Republic of the Congo, Côte d’Ivoire, the Democratic Republic of the Congo (DRC), Guinea, Niger, Nigeria, South Sudan, Togo, and Uganda. Preliminary data for 2023 reveal an alarming case fatality rate (CFR) of 11%.

The outbreak, which has affected both sexes with a male-to-female ratio of 1.7, has seen a median age of 25 years among cases, with 69% of cases being over 15 years old. However, the actual numbers might be higher due to suboptimal surveillance capacity in many affected countries. Fragmented data, limited integration with routine surveillance systems, and a lack of standardized case definitions contribute to underreporting and increased mortality rates.

Of particular concern is the active transmission reported in eight countries—Cameroon, Chad, Congo, DRC, Guinea, Niger, Nigeria, and South Sudan—during the last quarter of 2023 and up to February 25, 2024. These countries have already initiated response planning activities to contain the spread.

Moreover, Chad, Gabon, Niger, Nigeria, and Togo are awaiting the final classification of yellow fever laboratory samples through the plaque reduction neutralization test (PRNT). The situation underscores the urgent need for heightened surveillance and robust response measures across the region to prevent further escalation of the outbreak.