The controversy over whether to give a booster dose to healthy adults already vaccinated will live a key moment this Friday. The panel of experts from the FDA, the US drug agency, meets to discuss it. The agency will then have to decide whether or not to authorize the third dose of Pfizer-BioNTech for the general population. For now, the majority position of scientists is that this prick is not necessary, although the discussion remains open, also driven by variables such as policies – all governments wish to show themselves as the most prepared in the face of the pandemic – and commercial ones, with pharmaceutical companies trying to convince regulators of the benefits of a booster injection. The FDA already gave the green light on August 13 to the third dose for immunosuppressed patients. In this case, however, it was not about stopping the supposed immune loss, but about helping these people to reach the optimal level of defenses.
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Africa González, professor of immunology at the Center for Biomedical Research (CINBIO) of the University of Vigo, maintains: “Some immunosuppressed patients need three doses to achieve the same protection that the rest of the population gets with two. It is something that is also seen in older people, whose immune system weakens with age. But there is no evidence that in the rest of the population there is a loss of the immune response that requires a third dose ”.
This is essentially one of the two confronted positions. It is the one followed by Spain and the one presented by the European Medicines Agency (EMA, in its acronym in English) on September 2, when in a statement it defended that “there is, with the available evidence, an urgent need to administer a dose souvenir in already vaccinated adults ”. This sustained efficacy is the same for “all licensed vaccines” in the European Union (Pfizer-BioNTech, Moderna, Janssen and AstraZeneca).
The EMA, however, has not yet made a final decision and as of day 6 evaluates Pfizer-BioNTech’s request to authorize the third dose for those over 16 years of age “six months after receiving the second.” The agency plans to fix its position “in the coming weeks,” according to a statement. The application is based on a phase 3 trial with 306 participants and is pending publication in a scientific journal.
The position of extending the use of the third dose has been defended, in addition to the pharmaceutical companies, by some governments. The first to do so was Israel, which has given Pfizer-BioNTech a leading role in its fight against the pandemic in exchange for first ensuring the doses necessary to immunize the population. The United States followed suit a month ago when President Joe Biden promised to launch a campaign on September 20 to inoculate all already vaccinated adults with a booster dose.
Several scientists, however, have disputed the announcement as being made before — and not after, as would be expected — the FDA made a decision based on the available evidence. According to some analysts, it was the internal pressure from some governors and other figures in the face of announcements made by other countries and the fear of being left behind that led Biden to take the step. This has caused some tensions within the agency (two of its scientific advisers have announced that they will resign from their posts) and has led the White House into a delicate situation. John P. Moore, a virologist at Weill Cornell Medicine (New York), summarized it as The New York Times with the following words: “The Government said several weeks ago that the population needs a cake, that it deserves a cake and that it will have a cake. And now the population is waiting for their cake and will be angry if it is taken from them ”.
The United Kingdom, for its part, has opted for an intermediate option: offering the third puncture to those over 50 years of age and health personnel, in addition to the immunosuppressed.
As the date set for FDA experts to make a decision approaches, the debate over the third dose has intensified. It is no coincidence that the evidence that is being built in their favor comes precisely from Israel. An article published this Wednesday in the prestigious The New England Journal of Medicine concludes that the risk of contracting a severe covid among people over 60 who had received the third dose was up to 20 times lower than among those who had received only two.
The FDA has invited the head of the public health services of Israel and co-author of the study to present these conclusions in the committee this Friday. Experts, however, warn that observational studies are always subject to biases that can be very important in these cases, in a country, in addition, with about a quarter of the population that cannot be vaccinated because it is under 12 years and another 12% who have rejected it for religious reasons. “They are not comparable situations,” says Africa González.
Quique Bassat, epidemiologist and ICREA researcher at the ISGlobal institute (Barcelona), highlights the importance of another text published in recent days, in this case in the also prestigious The Lancet, by 18 eminent scientific figures, including members of the FDA itself and the World Health Organization (WHO). The study concludes that there is no solid evidence on the need for the third dose after reviewing the clinical trials and observational analyzes performed.
“This article is important because of its solvency and because it should help to reinforce the position that vaccination coverage of the unvaccinated population must be prioritized, most of whom live in poor countries, before thinking about the third dose for the population. general. It is something that the WHO was already saying, but rich countries do not tend to pay much attention to it, so it is important that the scientific community align itself and give strength to this position ”, Bassat concludes.
