Brazil has temporarily suspended the use of the world’s first single-dose dengue vaccine following two suspicious deaths. The decision was announced on Monday by health authorities as a precaution while investigations continue into the reported cases.

The vaccine had been widely rolled out across the country, with more than 500,000 people receiving doses between January and May. It was developed in Brazil and approved by health regulators in November. Officials said it was designed to simplify dengue prevention with a single injection instead of multiple doses, unlike other available vaccines.

Health data shows that out of 501,044 people vaccinated, about 3,703 individuals reported symptoms similar to dengue. Authorities also recorded 42 cases of more severe reactions. Three severe cases were identified in total, including two deaths involving a 58-year-old man and a 48-year-old woman. A third patient, a 38-year-old woman, was treated in intensive care but has since recovered and been discharged.

Despite the reported cases, Brazil’s Health Ministry said there is currently no confirmed evidence linking the vaccine to the deaths. Health Minister Alexandre Padilha described the situation as a “warning signal” but stressed that no cause-and-effect relationship has been proven. He also noted that clinical trials involving more than 16,000 volunteers did not show similar unexpected effects and recorded strong effectiveness against severe dengue cases.

Authorities have chosen to suspend vaccination temporarily while further safety reviews are carried out. Officials have not yet stated when or under what conditions the program may resume. The decision comes as Brazil continues to manage dengue outbreaks, having recorded more than 6,000 deaths in 2024. The ministry said it will continue monitoring the situation closely and update the public as more information becomes available.