Vaccine that protects against the omicron should not start until 2023, experts say

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The application of a booster dose with the bivalent vaccine containing the original strain of the Wuhan coronavirus combined with the omicron variant has already begun in much of the world.

Pfizer and Moderna have already licensed their Covid immunizers containing the BA.1 and BA.5 subvariants (from the omicron), the two forms of the virus with the greatest circulation today. This is because the vaccines produced in the first year of the pandemic, which use only the ancestral form in their formulation, have reduced efficacy against the new strains, mainly for the protection of mild and moderate cases.

In Brazil, there are already records of a new subvariant of the omicron, BQ.1.1. She was identified in São Paulo and caused the death of a 72-year-old woman who had comorbidities. The strain was also detected in Amazonas, Rio de Janeiro and Rio Grande do Sul. Experts warn that Covid cases are expected to increase in the coming weeks.

The bivalent vaccine has already been applied in the United States, Canada and Europe. Last month, Chile started boosting immunosuppressed people and healthcare professionals with the new formulation.

For infectologists, this is the scenario that Brazil should follow, although the Ministry of Health, in the current administration of Jair Bolsonaro (PL), says that the vaccination strategy for the next year, as well as the number of doses used, is still undefined.

“The ministry doesn’t say anything, but what we are seeing in the countries of the Northern Hemisphere is the update precisely with this bivalent vaccine. It would be interesting if this discussion had already started in the PNI [Programa Nacional de Imunização] next year”, says infectologist and researcher at Fiocruz, Julio Croda.

Today, there is a greater risk for people over 80 years of age, mainly of hospitalization and death, even with a booster vaccine, compared to young people, even if they are not vaccinated.

“The most important thing is that this bivalent vaccine can come to Brazil prioritizing these groups that have always been a priority in the past”, says Croda.

Another point still open is whether this vaccine will have to be updated every four or six months, the average time it takes for protection against symptomatic Covid to decrease, or if it will be annual, as is done with flu vaccination.

“The vaccine has fulfilled its role of brutally reducing the number of serious cases, hospitalizations and deaths”, says the infectious disease specialist and president of the immunization department of the Brazilian Society of Pediatrics, Marco Aurélio Sáfadi. According to him, it was expected that new applications would be necessary to accompany the mutations of the virus.

The infectologist points out that the time until the drop in the protection rate in vaccines against the coronavirus is relatively shorter than with other immunizers. “It is even shorter for the mild forms, but even the severe ones, after a while, there is damage to this protection. Which means that, after a while, it is necessary to apply booster doses”, he explains.

Sáfadi recalls that the flu vaccine has a similar duration of protection, of about six months, but, as influenza infections tend to occur more in the winter period, an annual flu vaccination is usually enough. “These two aspects make it very likely that we will have to carry out periodic, seasonal vaccinations, as soon as the virus takes on this role. [endêmico]”, it says.

For the researcher and coordinator of Fiocruz’s InfoGripe observatory, Marcelo Gomes, it is not yet possible to anticipate whether these variants that are in circulation will be dominant in the autumn and winter of 2023 in Brazil. “It is likely to be a descendant of the omicron, but we have no way of knowing which one it will be. Therefore, we need to think about the possibility of an annual booster”, he explains.

Therefore, he believes that the beginning of vaccination with bivalent forms in Brazil is still extemporaneous.

“Analyzing the benefits against the cost, giving a booster in the sense of recovering immunity is better, but it is not essential [agora]🇧🇷 Today, to recover the portions of the population that have not yet completed the primary vaccination schedule [duas doses] or did not start vaccination, like children under 5 years old, is fundamental”, he says.

For infectious disease specialist Rosana Richtmann, from the Instituto de Infectologia Emílio Ribas, a joint Covid and flu vaccination should be a good strategy, as it would generate a unique mobilization of the teams and the population, who will not have to go to the health post twice.

Even though it is not possible to know how the coronavirus will behave, as the last two and a half years have been atypical for a respiratory virus, she argues that the strategy against the virus includes updating immunizations.

“We are already seeing an increase in the number of cases in Brazil, but even if the next dominant virus is not the same that is in circulation now, three years is a long time to continue using the monovalent vaccine alone, so I believe it is necessary to think in the strategy [de reforço] bivalent”, he says.

Strategy still under discussion, says ministry

The Ministry of Health said, through a note, that the “vaccination strategy for the next year is under discussion by the PNI”, as well as the doses needed to “guarantee continuity in immunization against Covid-19”.

He also said that the folder “permanently monitors the evolution of vaccine coverage” at all ages and reinforces “the importance of the 2nd dose and booster dose to ensure maximum protection against the virus”.

Pfizer sent a request for authorization for the use of the bivalent vaccine against Covid to Anvisa (National Health Surveillance Agency) on August 19, but so far there has been no response.

Questioned, Anvisa informed, also in a note, that the process is still under analysis and that “requested the support of medical societies for the evaluation of data and issuance of an opinion”.

The body also reiterates that it considers the assessments of other international agencies in the request and that, “in the case of an authorization for emergency use, the process will still be forwarded for deliberation by the collegiate board”.

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