Ahead of the 30th United Nations Climate Change Conference (COP30), scheduled for November 10–21, 2025, in Belém, Pará state, Brazil, the Pan American Health Organization/World Health Organization (PAHO/WHO) is recommending that travelers — including heads of state, scientists, activists, and civil society representatives among the 60,000 expected attendees from 198 countries — review their vaccination status for yellow fever and measles before traveling.
Yellow fever is a serious viral disease transmitted by mosquitoes that can cause high fever, liver damage, and — in up to 50% of severe cases — death. So far in 2025, the Americas have reported 294 human cases, including 121 deaths, across six countries: Bolivia, Brazil, Colombia, Ecuador, Guyana and Peru. In addition, Costa Rica reported one imported case. While no cases have been reported in the city of Belém this year, its location in the Amazon region — a permanent risk area — requires caution.
Measles, a highly contagious viral disease, has made a global comeback, with 177,469 cases reported worldwide and 12,163 across 10 countries in the Americas as of mid-October, primarily among unvaccinated individuals or those with unknown vaccination status. Canada currently reports the highest number of cases in the region, while Brazil has recorded 35 cases during the same period — none of them in Belém.
While Brazil does not require proof of yellow fever or measles vaccination to enter the country, PAHO/WHO recommends the following:
- Individuals who have not been previously vaccinated should consider receiving one dose of the yellow fever vaccine (recommended for people aged 12 months to 59 years) at least 10 days prior to travel, and the MMR vaccine (measles, mumps, rubella — for those 12 months and older) at least 15 days before travel.
- For individuals aged 60 and older, yellow fever vaccination is recommended with caution and should be considered only after a personalized medical risk-benefit assessment.
- Both vaccines can be administered on the same day, or with a minimum interval of four weeks between them if given separately.
PAHO/WHO is calling on countries across the region to strengthen epidemiological surveillance, ensure vaccine availability in health services, and enhance risk communication targeting travelers and international delegations.
Health systems are also encouraged to monitor for possible cases among COP30 attendees, both during the event and after their return home — paying close attention to symptoms such as fever and rash (measles) or yellowing of the skin and eyes (yellow fever).
