Health officials warned of an ongoing yellow fever outbreak in São Paulo state on Wednesday, January 17; three fatal cases have been reported so far since January 1. Also on January 17, the Word Health Organization (WHO) advised all travelers to the state of São Paulo, including the city of São Paulo, to receive an immunization against yellow fever at least ten days before departure. The Brazilian government has since stated that the risk nevertheless remains low in urban areas.
Brazilian authorities plan to launch a new yellow fever vaccination campaign in February in São Paulo, Rio de Janeiro, and Bahia states. The campaign aims to vaccinate over 19 million people in 75 municipalities. Brazil suffered from a widespread yellow fever outbreak from December 2016 to June 2017, during which period hundreds of cases were reported. The outbreak notably spread to urban areas of the southeastern states of Rio de Janeiro and São Paulo. Prior to 2017, yellow fever outbreaks had not occurred in urban areas of Brazil since 1942.
Symptoms of yellow fever - a mosquito-borne disease - generally appear within three to six days following infection and include fever, chills, muscle and back pain, vomiting, headaches, and, in more serious cases, hemorrhaging, and organ failure. The vaccine provides life-long immunity.
Individuals in or planning travel to São Paulo are advised to stay abreast of local epidemiological developments, consult their doctor regarding vaccination options, and continue to protect themselves against insects due to the presence of various other mosquito-borne diseases (dengue fever, chikungunya, Zika virus, etc.), e.g. by wearing covering clothing, using insect repellent, and sleeping in screened-in and/or air conditioned rooms.
A full list of zones where the World Health Organization (WHO) recommends vaccination is available here.