Butantan's dengue vaccine maintains protection for five years and reduces serious cases The vaccine developed by the Butantan Institute against dengue, whose use was suspended by the Ministry of Health this Monday (8), was developed to prevent infection by the four serotypes of the virus and offers protection for at least five years. (see more details below) ➡️The decision was taken after the identification of "42 episodes of more severe reactions that are temporally associated with the moment of application of the vaccine", stated the Minister of Health, Alexandre Padilha. Among these, there were unexpected effects, including two deaths. According to the minister, in previous studies carried out with the vaccine, the reactions observed when applying 500,000 doses in Brazil had not been reported. In the study published in the journal "Nature Medicine" in March, for example, serious adverse events occurred in similar proportions among vaccinated people and participants who received a placebo, with no signs of safety problems related to the vaccine. Despite the announcement of the temporary discontinuation of the use of the vaccine, it is still not possible to establish a causal relationship between the application of the vaccine and deaths. The cases will still be investigated. Butantan dengue vaccine. Government of São Paulo/Disclosure How does the vaccine act in the body? The Butantan-DV vaccine is the first 100% Brazilian vaccine against dengue and works with a single dose. It was developed to prevent the four serotypes of the dengue virus — DENV-1, DENV-2, DENV-3 and DENV-4. The immunizer works by stimulating the body to produce its own protection Proven effectiveness The study that followed more than 16 thousand participants aged 2 to 59 years, the overall effectiveness of the vaccine was 65% against symptomatic dengue confirmed by examination after five years of follow-up. Protection against severe dengue or with warning signs was even greater, reaching 80.5%. A new long-term analysis of the dengue vaccine developed by the Butantan Institute indicates that a single dose of the vaccine maintains protection for at least five years and significantly reduces the risk of severe forms of the disease. The results were published in the scientific journal Nature Medicine and are part of the follow-up of a phase 3 clinical trial carried out in Brazil. The research also showed that the vaccine was effective both in people who had already had dengue fever and in those who had never been infected. See the videos that are trending on g1 Among individuals with previous exposure to the virus, the effectiveness was 77.1%, while in participants without previous infection it was 58.9%. For Kfouri, these numbers reinforce the potential of the vaccine as an important tool to reduce hospitalizations and deaths from the disease – even if it does not completely eliminate the circulation of the virus. Greater protection against serious cases Infectious disease specialist Renato Kfouri, vice-president of the Brazilian Society of Immunizations, explains that this behavior is expected in vaccines against viral diseases. According to him, the main objective of immunizations is not necessarily to prevent all infections, but to avoid the most dangerous forms of the disease. "The effectiveness of vaccines is usually greater for the most serious outcomes. This happens with flu, Covid-19 and other infections. The most important thing is to reduce hospitalizations and deaths", says Kfouri. In the study, no cases of severe dengue fever were recorded among vaccinated participants during follow-up, while severe episodes occurred in the placebo group. Challenge of the four serotypes Dengue is caused by four different serotypes of the virus — DENV-1, DENV-2, DENV-3 and DENV-4. The Butantan vaccine was developed to protect against all of them. However, during the period in which the clinical trial took place in Brazil, only two types circulated widely: DENV-1 and DENV-2. Therefore, the study was unable to directly assess protection against the other two serotypes. Kfouri says this gap doesn't necessarily mean the vaccine won't work against them. "In laboratory studies, we see the production of antibodies against the four serotypes. But, as dengue 3 and 4 did not circulate in Brazil during the study period, it was not possible to demonstrate this protection in practice", he explains. According to him, ongoing research in other countries can help clarify this issue. Security is central Safety assessment was one of the main focuses of the study. Dengue presents a phenomenon known as antibody-dependent increase, in which a second infection with the virus can lead to more serious conditions. Therefore, experts consider it essential that dengue vaccines do not increase this risk. “Five-year follow-up is essential precisely to ensure that the vaccine does not act as a previous infection that could worsen future dengue fever”, says Kfouri. In the study, serious adverse events occurred in similar proportions between vaccinated and placebo participants, with no signs of safety problems related to the vaccine. Vaccine does not replace mosquito control Even with the arrival of new vaccines, experts warn that controlling the Aedes aegypti mosquito remains essential. This is because no immunizer offers total protection against the disease, and the circulation of the virus depends on the presence of the vector. "Vaccination and combating mosquitoes need to go hand in hand. When we reduce the number of susceptible people and also reduce the number of mosquitoes, transmission tends to fall", says Kfouri. According to him, this combination can even generate indirect protective effects, benefiting even people who have not been vaccinated. Butantan's dengue vaccine will be administered in a single dose