The Brazilian government has temporarily suspended the nationwide rollout of the world’s first single-dose dengue vaccine after reports of two deaths and 42 serious adverse reactions among approximately 500,000 vaccinated individuals.

Health authorities confirmed that the 42 cases—representing 0.008 percent of doses administered through May 30—include the deaths of a 48-year-old woman and a 58-year-old man, along with one patient requiring intensive care before discharge. While no conclusive evidence directly links these incidents to the vaccine, officials described the pause as a precautionary measure to ensure safety during ongoing investigations by the Ministry of Health, Anvisa, and the Butantan Institute.

Health Minister Alexandre Padilha emphasized that the suspension does not question the vaccine’s efficacy, noting clinical trials prior to approval demonstrated protection against symptomatic dengue and hospitalizations with over 74 percent effectiveness. The suspension aims to allow thorough evaluation while maintaining confidence in Brazil’s safety monitoring system.

Developed by the Butantan Institute using U.S. technology, the vaccine—known as Butantan-DV—was approved in late 2015 and began mass vaccination in January 2026. Brazil launched its campaign targeting healthcare workers and individuals aged 15 to 49 in northern Tocantins state after dengue infections surged to 6.5 million probable cases in 2024, affecting over 20 million Brazilians since the 2000s.

The Ministry of Health confirmed that the suspension does not invalidate the vaccine’s protection for those already immunized and stated the decision reflects Brazil’s robust safety protocols. Dengue, a mosquito-borne disease causing high fever and severe complications in extreme cases, remains a growing global health challenge with dengue cases reaching historic levels worldwide.