Yellow Fever Risk Remains High in São Paulo

The Pan American Health Organization (PAHO) recently confirmed that the overall risk associated with the yellow fever situation in the Americas Region, particularly in endemic countries such as the Federative Republic of Brazil, is classified as ¨High¨.

As of June 24, 2025, mosquito-borne transmissions of the yellow fever virus (YFV) have been confirmed throughout the states, including São Paulo State. 

The YFV was detected in two distinct geographic locations in São Paulo, between September 2024 and February 2025. Phylogenetic analysis of six new genomes revealed a reintroduction in 2022 from Midwest Brazil

According to Brazil's Ministry of Health, yellow fever is an acute, vaccine-preventable, febrile infectious disease with high mortality rates in its severe forms. There is no evidence of person-to-person transmission, so avoiding mosquito bites is crucial.

Vaccination is the primary tool for preventing yellow fever in Brazil.

Since April 2017, Brazil has adopted a vaccination schedule of only one dose for life, a measure that aligns with the World Health Organization's recommendations.

When visiting Brazil and other areas endemic for yellow fever in 2025, the U.S. CDC recommends being vaccinated at least 10 days before departure. The YF-VAX vaccine is available at certified travel clinics and pharmacies in the United States.