HEALTH: A vaccine against dengue fever proves its effectiveness

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Thousands of people in overseas territories are affected each year by the dengue virus. The recent epidemic in Saint-Martin has once again demonstrated that no one is safe from this viral infection transmitted by mosquitoes.

Until now, there is no treatment for dengue fever other than taking paracetamol to reduce the symptoms of fever, a course of vitamins, good hydration and plenty of rest. Although two vaccines are currently available on the market, they are not recommended by the High Authority of Health: Dengvaxia (Sanofi Pasteur) in three doses which has proven dangerous for people who have never contracted dengue and Qdenga (Takeda ) in two injections which obtained market authorization on December 5, 2022 and can be used for everyone but does not protect against the 4 serotypes of dengue. In testing since February 2016 in a Brazilian laboratory, the single-dose vaccine called “Butantan-DV” revives hope for the thousands of people affected by the disease and those who fear contracting it.

The promising results of the phase 3 trial were published in the New England Journal of Medicine: out of 16.235 people aged 2 to 59 years in 13 states of Brazil, 10.259 participants received the Butantan-DV vaccine and 5.976 a placebo. Protection against infection was 80,1% for 2/6 year olds, 77,8% for 7/17 year olds and 90% between 18 and 59 year olds. The vaccine “also proved to be extremely safe for people who have never had dengue fever, which is an advantage,” underlines virologist Maurício Lacerda Nogueira, one of the trial coordinators: 73,6% of participants had never contracted dengue and 89,2% had already been exposed. Against serotype 1 (DENV-1), the effectiveness of the Brazilian vaccine was 89,5% and 69,6% against serotype 2 (DENV-2). If serotypes 3 and 4 “were not detected during the monitoring period, the results of phase 2 showed that the four attenuated viral serotypes of Butantan-DV (…) induce a balanced response in terms of production of antibodies. This leads us to conclude that its effectiveness against DENV-3 and DENV-4 will be equally good,” specifies ML Nogueira. Other good news is that the unwanted side effects were mild or moderate (pain and redness at the injection site, headaches and fatigue). Serious effects were seen in less than 0,1% of all vaccinated people, who recovered. Next June, the five-year monitoring period will end to make way for the consolidation of data which will make it possible to know "how long the protection induced by the vaccine will last" explains Dr Esper Kallás, first author and director of the Butantan Institute. A first request for registration of the vaccine with the Brazilian authorities is planned for the second half of 2024 with the hope of final approval of the vaccine in 2025. _VX

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