Countries: Brazil, Bolivia (Plurinational State of), Comoros, Ecuador, Guyana, Peru, Venezuela (Bolivarian Republic of) Source: Pan American Health Organization Please refer to the attached file. Since September 2024, cases of yellow fever have been reported in areas with no history of transmission, including cases identified outside the Amazon region. In response to this situation, the Pan American Health Organization / World Health Organization (PAHO / WHO) is reinforcing its call to Member States to strengthen surveillance, intensify vaccination of at-risk populations, and take the necessary measures to ensure that people traveling to areas with reported cases are properly informed and protected against yellow fever. In addition, it highlights the need to strengthen clinical management, with an emphasis on the detection and timely treatment of severe cases. PAHO/WHO also recommends having reserve doses available, according to the availability of vaccines in each country, to ensure a rapid response to possible outbreaks. Summary of the situation Between epidemiological week (EW) 1 and EW 53 of 2025, 346 confirmed human cases of yellow fever were reported in seven countries in the Americas Region, including 143 deaths (case fatality rate [CFR] 41%) (1-10). This represents a 5.6-fold increase compared with 2024, when 61 confirmed cases of yellow fever were reported (Figure 1). In 2025, cases were reported in: the Plurinational State of Bolivia (n= 8 cases, including two deaths), Brazil (n= 120 cases, including 48 deaths), Colombia (n= 125 cases, including 46 deaths), Ecuador (n= 11 cases, including eight deaths), Guyana (one death), Peru (n= 49 cases, including 19 deaths), and the Bolivarian Republic of Venezuela (n= 32 cases, including 19 deaths) (Figure 2) (1-10). In 2026, between EW 1 and EW 7, 34 confirmed human cases of yellow fever were reported in four countries in the Americas Region, including 15 deaths (CFR: 44%) (1-10). Cases were reported in: the Plurin