Two US health regulatory agencies, the Drug and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC), this month approved the application of mRNA vaccines against the new coronavirus in children from six months of age. Previously, these vaccines were only approved for children over the age of five.
Pfizer, after obtaining FDA and CDC approval, now asks Anvisa for authorization to the same age group in Brazil. The baby vaccine is diluted tenfold compared to the adult dose.
The New York Times, covering the issue, said that “some parents may not be interested because their children were among the 37% of children who may have already been infected. But vaccination gives more powerful and consistent protection even if a child has already been infected.” The sources are the scientists on the CDC advisory committee who approved the measure.
“They don’t know if this is true,” says Vinay Prasad, professor of epidemiology and biostatistics. at the University of California at San Francisco, on their social media. “This is based on nothing. At best, they could say that, although some people speculate that this is the case, we currently do not have evidence on a large scale [de estudos] randomized”, which are those more rigorous studies that randomly choose two to three groups: who receives the treatment, who does not receive and (in some cases) who receives an innocuous treatment, the famous placebo.
Less rigorous studies with good samples, but still useful, such as the observational data are also not available for this age group. All we have are preliminary studies by the manufacturers themselves, with small samples.
The method problems in the recommendation
The Brown University School of Public Health published a three-page pamphlet that would serve as a summary of the evidence in favor of vaccinating infants and young children against Covid. The document says that “We know, from the vaccination of young people from five to 17 years old, that hospitalization, the most critical and deaths are more common among the unvaccinated than among the vaccinated and booster”. The statement is true, but potentially confusing for parents who want to know whether the vaccine in little ones will reduce their risk of contracting, getting sick or dying from Covid. Parents want to know if there is a causal relationship between the vaccine and the lower risk, while what is being offered is an observation that less risk and receiving the vaccine go together, without compromising the idea that the latter causes the first. In the population, greater height occurs along with gray hair, but it does not mean that the causal factor for gray hair is height: it is aging.
The pamphlet cites as a source for the statement an article by Ashley Price, a researcher at the CDC, and more than 40 other authors from this and other institutions. The method of this study of vaccine efficacy in children and adolescents is known as “test negative case control”. The purpose of this method is to prevent patients seeking hospital treatment from distorting the sample too much: there are patients who have sought hospital treatment and are vaccinated, there are patients who have sought hospital treatment and are not vaccinated (negative controls), and the comparison of the two groups would be useful. to calculate the effectiveness of the vaccine.
However, as in this case, children hospitalized with and without the vaccine are being compared. Both groups are sick children, which means that those vaccinated are likely to have a higher concentration of those who were vaccinated because they have comorbidities, for which there is little doubt that the vaccine is most needed. What is at issue is whether the Covid vaccine is necessary for all children, including healthy ones.
This methodology has led to misinformation in medicine before. In 1981, the famous medical journal NEJM published a study that found an association between drinking coffee and developing pancreatic cancer. The problem was precisely that the negative controls had diseases such as peptic ulcer, for which doctors recommend drinking less coffee. It’s not that pancreatic cancer patients drank too much coffee: the hospitalized people they were compared to drank too little coffee. The association existed, but it was not a causal relationship.
Questionable percentages of efficacy
Brown’s pamphlet also mentions that “children [a partir dos cinco anos] vaccinated had fewer infections. Vaccines reduced the rate of any infection between 37 and 80%. Although the overall number of cases was low, there is an expectation that both vaccines [Pfizer e Moderna] will lower hospitalizations and intensive care too.”
“Some of us want data, not expectations,” says Prasad. He points to the source of these percentages. The 37% come from the pharmaceutical company Moderna, which makes the other mRNA vaccine that did not come to Brazil, because, according to Anvisa, there was no request of import, emergency use authorization or registration — but there will be for use on young children. This effectiveness is based on Covid tests done within Moderna’s own study, excluding home tests available in the United States. When these are included, the vaccine efficacy drops to 28, 5%. The 80% are from Pfizer. Here, the pamphlet fails to mention the uncertainty of this number, which, in the original documents published by the FDA, has a large “margin of error” that ranges from no efficacy to near-perfect efficacy. This is often a problem with small samples.
The FDA’s own emergency authorization document for the Pfizer vaccine in children six months and older says about its efficacy in this group, that “an additional analysis regarding the occurrence of cases of Covid-19 was determined to be unreliable due to the small number of cases of Covid-19 that occurred in the study participants”.
Two medical scientists left the FDA in protest in the second half of 80: Dr. Marion Gruber, former head of the agency’s office of vaccine research and review, with 32 years of service; and her subordinate, Dr. Phil Krause. The FDA did not give reasons for the scientists’ resignation from their posts, but Endpoints News, a news site specializing in the world of biopharmaceutical research affiliated with the University of Kansas, cites frustrations with the Biden administration’s rush to apply the booster dose by running over protocols. , and the CDC’s usurpation of FDA functions.
Republican Senator Rand Paul said in a session of a US Congressional committee that the Institutes Nationals of Health refuse to release the names of a thousand scientists employed by the institutes that receive money from the intellectual property of vaccines and have, therefore, conflict of interest as regulators who decide whether these vaccines will be approved.
In conclusion, there is still a lot of ignorance about whether it is really necessary to vaccinate against Covid children in general, and children from six months to five years in particular. The benefit of vaccination against Covid may become clearer in children with comorbidities and immune deficiencies. The 37 % of children who have already had Covid in the United States may be an underestimate, the natural immunity among them is high and offers some protection. We also don’t know whether the protection of natural immunity is as good on its own as supplemented by vaccines. While the benefit of traditional vaccines given to children, such as the MMR, is clear, the benefit in the case of Covid vaccines 37 remains unclear. .