Brazil has temporarily suspended the rollout of the world’s first single-dose dengue vaccine following reports of two deaths and dozens of serious adverse events among recipients, prompting a nationwide investigation.
According to TrialSiteNews, the vaccine, developed by the government-backed Butantan Institute and approved in late 2025, had been viewed as a major breakthrough in combating dengue due to its single-shot design. More than 500,000 people, largely healthcare workers, received the vaccine during the first five months of 2026.
Health authorities recorded 3,703 reports of symptoms resembling dengue infection, while 42 cases were classified as serious. Investigators are closely examining the deaths of a 58-year-old man and a 48-year-old woman, as well as a severe case involving a 38-year-old woman who later recovered.
Brazilian health bureaucrats claimed there is no evidence proving the vaccine caused the events. The suspension has been described as a precautionary step while regulators assess medical records, underlying health conditions and alternative explanations.
The move comes despite clinical trials involving more than 16,000 participants reporting strong protection against severe dengue and no comparable safety concerns. The outcome of the investigation could influence future dengue vaccination programmes across Latin America and beyond.
