The dengue vaccine developed by the Butantan Institute in São Paulo, Brazil was 80.5% effective against severe dengue cases over a five-year period.
It was also 65% effective in preventing symptomatic dengue.
The phase 3 clinical trial conducted at 16 research centres across Brazil involved 16,235 participants between the ages of two and 59 years.
Of those, 10,259 received a single dose of the vaccine, while 5,976 received a placebo.
There were no reports of hospitalisation in the vaccinated group, compared to eight cases in the placebo group.
Called Butantan-DV, the tetravalent vaccine protects against all four known serotypes of the dengue virus.
It uses live viruses that have been “weakened” (attenuated) in a laboratory setting so that they cannot cause disease, yet are still able to stimulate an immune response.
The vaccine was approved by the Brazilian Health Regulatory Agency (ANVISA) on Nov 26, 2025, for use in the Brazilian population aged 12 to 59.
The results of the clinical trial was published on March 4 (2026) in the journal Nature Medicine. – Agência FAPESP
