Infectious disease specialist explains pharmacovigilance system for vaccines

The Ministry of Health suspended, on Monday (8), the application of the dengue vaccine produced by the Butantan Institute. The preventive measure was adopted after 42 serious adverse reactions and two deaths were recorded, which are being investigated by health authorities.

Doctor and infectious disease specialist Luana Araújo explained to Live CNN that the events recorded were classified as unexpected, as they were not observed during the vaccine development process, which included testing on approximately 16 thousand people. According to her, the Ministry of Health itself highlighted this unexpected nature during a press conference.

Pharmacovigilance and the role of post-approval monitoring
Luana Araújo highlighted that the emergence of unforeseen reactions after a product enters the market is something that can occur within the regulatory process. "To a certain extent, that's what happens even when these products go to market," he said.

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For this reason, according to the infectious disease specialist, there is a pharmacovigilance system conducted in an "ostensive, sensitive and assertive" manner, capable of identifying events that were not observed in clinical studies.

"The slightest possibility of being linked to the vaccine already causes this system to be paralyzed so that this can all be investigated in a deeper way", highlighted the specialist.

The Butantan vaccine is different from the one used in the public network for children
Luana clarified that the suspended vaccine is different from the one already available in the public network for children and adolescents. The vaccine applied in the SUS (Unified Health System) for children and young people, between 10 and 14 years old, is produced by Takeda, in two doses, and is not related to the events investigated.

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The Butantan Institute vaccine, with a single dose, was initially applied to health professionals and, in some cities, to a slightly broader group. "Whoever made the Takeda vaccine has no reason to have any concerns about what is happening now," said Luana Araújo.

Both vaccines use attenuated virus technology - that is, weakened viruses -, which makes them effective, but also imposes restrictions on their use. Pregnant women, immunosuppressed people and the elderly (still being studied) should not receive them.

The fundamental difference between them, according to the infectious disease specialist, lies in the manufacturers and formulations, which are completely different.

How vaccine technology works
The doctor also explained the basic principle of vaccines. According to her, the vaccine is "a way of teaching our body to defend itself without it having to go through the stress of the disease".

There are different technologies for this: inactivated virus, attenuated virus, mRNA and proteins, among others. In the case of vaccines with an attenuated virus, the body is immunologically stimulated by a weakened virus that, in most people, does not cause disease.

However, in individuals with a compromised immune system, even the weakened virus can eventually cause illness, which justifies application restrictions.

The specialist also took the opportunity to reinforce the importance of vaccines in general. "Vaccines have saved millions of lives over the last few decades, and they continue to do so. Not only do they save lives, they also save the health system and preserve people's quality of life", concluded Luana Araújo.

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Source: CNN