Dengue vaccine is safe, experts say – 03/12/2024 – Health

The dengue vaccine is considered safe by experts, despite recorded cases of allergic reactions. The Ministry of Health identified 70 cases after applying 365,610 doses.

Because of this, the ministry’s new recommendation is that children and adolescents who are the target audience be observed for 15 to 30 minutes after applying the vaccine.

Those who do not have a history of severe allergies must wait 15 minutes, while those who do must undergo observation for 30 minutes. Furthermore, vaccination units must have availability of medications to treat anaphylaxis (severe allergic reaction), such as adrenaline, antihistamines and corticosteroids.

“The vaccine is safe. Allergic reactions, especially mild ones, are common and can happen to any drug. Events like these are considered extremely rare”, says infectious disease specialist and professor at Unesp, Alexandre Naime Barbosa.

Of the total of 70 reactions, only 16 were considered serious, characterized by anaphylaxis, according to a technical note from the Ministry of Health. Symptoms include skin irritation, nausea, vomiting, difficulty breathing and hemorrhagic shock. Mild cases, the majority, may include the manifestation of redness and pain in the area of ​​application.

According to Takeda, the pharmaceutical company responsible for producing Qdenga, clinical studies involved more than 28 thousand people aged 1.5 to 60 years in 13 countries over 15 years and demonstrated the vaccine’s effectiveness in reducing 80.2 % of symptomatic dengue cases and 90.4% of hospitalizations.

“The data supported the rigorous evaluation by regulatory bodies for the approval of the vaccine in Brazil and also culminated in the recommendation of the vaccine by the WHO (World Health Organization)”, says the note.

During clinical studies, no serious hypersensitivity reactions or cases of anaphylactic reactions were reported. But, according to experts, when the vaccine is introduced on a large scale, adverse or rare events may occur.

“I have no doubt that the risk and benefit ratio remains unchanged for this vaccine, and no one considered suspending vaccination. We have a very attentive adverse event surveillance system to report cases, which has existed in the country for a long time “, says the vice-president of the Brazilian Society of Immunizations (SBIm), Renato Kfouri.

One of the possibilities raised for the occurrence of these reactions is that there may have been incorrect handling of the vaccine, says Alexandre Barbosa, who is also coordinator of the Brazilian Society of Infectious Diseases, a body that is represented in the Technical Advisory Chamber on Immunization. The analysis of the cases was conducted by the Ministry of Health in collaboration with the Chamber and the Interinstitutional Committee for Pharmacovigilance of Vaccines and Other Immunobiologicals on Thursday (7).

The immunizer needs to rest for a while at room temperature after being removed from refrigeration. Experts are studying the chance that, if the specified period is not followed, the person may receive a higher content of the vaccine and have a reaction.

Another possibility is that the reactions were triggered by some component of the vaccine. But, according to Kfouri, there is no specific characteristic in common among the individuals who had reactions.

Although the cause of the reactions is not yet known, they all resolved spontaneously and there were no cases of hospitalization. “We will observe with a larger sample whether this effect is reproduced on a larger scale,” he says.