09/21/2023 – 6:21
After more than 540 million doses applied in almost three years, in 2023 Brazil is experiencing a period of transition in vaccination against Covid-19, from emergency campaigns to immunization
routine. The assessment was made on Wednesday (20) by the director of the National Immunization Program (PNI), Eder Gatti, at the National Immunization Day, held by the Brazilian Society of Immunizations (SBIm), in Florianópolis. The director said that the municipalities have been working for practically three years on a vaccination campaign against Covid, but the change in the epidemiological scenario of the disease requires the incorporation of this vaccine into the program calendar.
In 2023, the Ministry of Health extended vaccination with bivalent booster doses to the entire population over 12 years of age. Adherence, however, was low even for priority groups, considered to be at greater risk of worsening the disease. While 516 million doses of monovalent vaccines were administered in the country, only 28 million bivalent vaccines were administered, of which only 217,000 were administered to adolescents.
For 2024, the proposal still being developed is the adoption of a routine vaccination schedule against Covid-19 for children under 5 years of age, and periodic booster doses at least once a year for risk groups, such as the elderly, immunocompromised (patients with weakened immune systems)
and pregnant women, following guidance from the World Health Organization (WHO). There is also the possibility of including other groups such as health professionals and traditional communities.
“Vaccinating the entire population, as we have been doing, needs to be reviewed in this moment of transition in which we find ourselves. We held technical meetings and drew up basic guidelines that the Ministry of Health will follow in internal discussions. Now, the announcement of this still depends on a discussion with the tripartite management [governo federal, estados e municípios]”, says Gatti.
“Today, we have made progress both in the evaluation of the international recommendation, from the WHO, and in the discussion with experts, but we need to move forward in this agreement”, he adds.
The PNI director intends to start a routine vaccination strategy against Covid-19 at the beginning of 2024, to replace the “exceptional nature”, with constant changes, which still dictates the pace of immunization against the disease.
“Covid-19 needs to stop being a campaign strategy and become a permanent recommendation. We hope to make official announcements with the most complete strategy before the end of the year.”
Gatti emphasizes that surveillance of variants must be constant, because they are the ones that have determined the waves of infection since the beginning of the pandemic. This behavior differs from other respiratory-transmitted diseases, whose incidence is more influenced by the seasons. While it is important to have up-to-date vaccines against these variants, he argues that more important is ensuring that vaccination takes place.
“THE SAGE [grupo consultivo de vacinação da OMS]
It doesn’t talk so much about which vaccine should be given. The WHO guides how the composition of the vaccine should be, now there is a certain freedom regarding which vaccine to use”, ponders the director of the PNI, who adds that the program’s positioning will be to make available vaccines available, preferably in the latest licensed and updated version against variants. “The Ministry of Health’s next acquisitions will follow this logic. They will probably be messenger RNA vaccines with the compositions placed in accordance with licensing.”
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To guarantee national vaccines using the messenger RNA platform, which is more versatile in the fight against coronavirus, the Ministry of Health has supported its own developments from the Institute of Immunobiological Technology (Bio-Manguinhos) and the Butantan Institute. Gatti considers that the ideal is for a national messenger RNA technology to be available to the PNI, since the vaccines against Covid-19 offered by these laboratories to date are from other platforms.
“We hope to begin clinical trials of this Brazilian RNA vaccine platform soon. This is a technology that is important for us to master, because it allows us to develop vaccines more quickly and for other infectious agents as well. We need to look for this and we are on that path.”
Race against the virus
The secretary of the Immunization Department of the Brazilian Society of Pediatrics and representative of SBIm in Pernambuco, Eduardo Jorge da Fonseca, describes that the transition to routine vaccination against Covid-19 is under discussion around the world. The United Kingdom, for example, decided to adopt the vaccine recommendation for the priority groups suggested by the WHO. Another part of Europe and the United States have extended vaccination to the entire population.
“At the current moment, we have evidence of the importance of maintaining boosters with the bivalent vaccines available in Brazil. There is no consensus on whether we should revaccinate everyone. Probably, here too, we will adopt vaccinating the highest risk groups with the updated vaccine. But we need to ensure we increase the coverage of vaccines already available, especially pediatric ones.”
The constant race to keep vaccines up to date against circulating strains has been won by the SARS-CoV-2 coronavirus, which continues to undergo new mutations to acquire immune escape. Vaccines remain proven to be effective in reducing
the severity of their infections, but they are unable to neutralize them or block the virus, which is always one step ahead in its accelerated evolution. An example of this is the monovalent vaccine against the XBB variant, which arrived in the United States at a time when the dominant variant was EG.5, and with BA.2.86 already on the rise.
“With Covid, time started to flow much faster”, warns Fonseca.
“We do need a vaccine with longer protection, that is variant-proof.”
Despite this need, he reinforces that current vaccines can significantly reduce the chances of hospitalization
or death
per
covid-19, even when they are not directly updated with the “latest version” of the coronavirus. Therefore, it is necessary to expand
vaccination coverage with bivalent booster doses and also protecting children who did not have access to the initial two-dose schedule.
Evolutionary leap
The development of a generic vaccine that protects not only against all variants of SARS-CoV-2, but also against all coronaviruses is an objective of research working to maintain control of the pandemic, says biologist José Eduardo Levi, researcher at the USP Tropical Medicine Institute. SARS-CoV-2, however, has behaved in a completely unpredictable way.
“The virus continues to evolve, and we continue to be at risk of getting out of control. I do not share this perception that the pandemic is over”, he says, who believes that the immunity from vaccines added to the natural immunity generated by the infection has protected a large part of the population from serious cases, however
also pressured the virus to evolve further to continue circulating.
“There is an exchange of dominant variants every four, five months. This is completely unforeseen and is due to this selective pressure.”
He warns that the new variant on the rise in the United States and the United Kingdom, BA.2.86, has made an evolutionary leap comparable to what the omicron variant represented in relation to its predecessors. The researcher says that there are those who consider the omicron a “SARS-CoV-3”, because it completely altered the behavior of the pandemic, producing a much more accelerated wave of cases.
“Before omicron, the variants of concern did not descend from each other, they all came from the ancestral variant. After omicron, all the variants that became predominant were variants derived from omicron. Evolutionary history changes.”
Levi highlights that it is important to vaccinate especially immunocompromised people. In addition to having a greater risk of dying from Covid-19, these people, when infected, can offer more chances of mutations to SARS-CoV-2, which remains in the body for longer without being neutralized by
defenses. This happens because SARS-CoV-2 manages not to evolve through mutations, but also through deletions, which are eliminations of parts of its structure that already cause a reaction in the body’s defenses. By losing these pieces, the virus again confuses the immune system.
“The theory proven today is that these variants appear mainly in the bodies of people with immunodeficiencies. A classic study followed an immunodeficient patient for 180 days and, gradually, there is an accumulation of mutations and deletions. So much so that, on day 180, the patient remains ill and dies with a virus completely different from the virus that entered.”
*The reporter traveled to Florianópolis at the invitation of the Brazilian Society of Immunizations (SBIm)
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