Children used as guinea pigs by a pharmaceutical laboratory unable to say if its vaccine against Covid-19 is safe for them … On social networks, many Internet users share an article posted Monday, November 15 on the Le Libre site Thinker, regularly pinned for his conspiratorial content. “Pfizer admits that it takes ‘5 years’ to study the risks of myocarditis and pericarditis in children”, announces the publication, which adds: “According to them, the number of participants in the current clinical trial is too small to detect the risks.”
The Free Thinker endorses the anti-vaccine rhetoric, ensuring that “children are in danger”, because they “participate in a wild-type clinical trial”, himself “extremely dangerous”, “given the large number of adverse effects already listed”. “The lab itself doesn’t know what it’s doing”, claims the site, which wants as proof of its assertions an extract of a “official document” available on the website of the FDA (Food and Drug Administration), the American drug agency, since “more than two weeks”, but of which “no French media [ne] speak”. But is he saying true or fake?
The mentioned document * originates from Pfizer. The laboratory takes stock of the clinical trial of its vaccine against Covid-19 on children aged 5 to 11. This very detailed summary (81 pages) was prepared as part of a meeting of an FDA advisory committee *, held on October 26. The American agency brings together in these committees * scientific experts, but also members of civil society, so that their analyzes, their remarks and their advice inform decision-making on the medical products examined.
This long note takes stock of the results of the clinical trial, also published in the New England Journal of Medicine (NEJM) * on November 9. This is a randomized, double-blind study, a standard in medical research. In other words: neither the patients nor the caregivers know whether they are receiving or administering the treatment or the placebo, and the two groups of patients (test and control) are drawn. This phase 2-3 trial was carried out after a first phase 1 trial on a small group of 48 children. This time the sample is larger: 2,268 children, aged 5 to 11. Of these, 1,518 received the vaccine and 750 received a placebo, a proportion of two-thirds to one-third. The vaccine was injected in two doses, three weeks apart. Children received doses three times smaller than adults: 10 micrograms instead of 30 micrograms. They were then followed for at least two months after the second injection.
The results obtained in children were compared with those obtained in young adults. Conclusion: they are “comparable”, observe in a joint press release the French learned societies of pediatrics (SFP) and infectious pathology (Spilf). Immunogenicity, that is, the ability of the vaccine to elicit an immune response, is similar. The antibody level was on average 1,197 among 5-11 year olds and 1,148 among 16-25 year olds. The efficacy of the vaccine on symptomatic forms of the disease is 90.7%. Three cases of Covid-19 occurred in the vaccinated group (out of 1,305 children evaluated) against 16 in the placebo group (out of 663 children evaluated). Again, this proportion is similar to that observed in adults. Same observation for the tolerance of the vaccine by children: the most frequent side effects (pain at the injection site, redness, fever, etc.) were comparable to those observed in adults.
But a paragraph on page 11 of this document catches the attention of critics of the Covid-19 vaccination. We read this: “The number of participants in the current clinical development program is too small to detect any potential risk of myocarditis associated with vaccination. The long-term safety of the Covid-19 vaccine in participants aged 5 to less than 12 years will be investigated. in 5 post-authorization safety studies, including a 5-year follow-up study to assess the long-term sequelae of post-vaccination myocarditis / pericarditis. ” For the experts interviewed by franceinfo, this passage does not call into question the conclusions of Pfizer, as the contemptors of vaccines think.
“Myocarditis and pericarditis are secondary inflammatory reactions which result in damage to the heart muscle”, explains Romain Basmaci, general secretary of the SFP and head of the pediatrics department at the Louis-Mourier hospital in Colombes (Hauts-de-Seine). “The symptoms are chest pain, shortness of breath, fatigue after exertion, or fever, but not always. This is treated with anti-inflammatory treatment with corticosteroids.”
The risk of myocarditis after vaccination has already been identified in young adults under the age of 30, rather in men. However, it is lower with the Pfizer vaccine than with Moderna. It generally appears within seven days of vaccination, in particular after the second dose, recalls the Epi-flagship scientific group (led by Cnam and ANSM), which studied it. In the case of the Pfizer vaccine, only three in a million cases were identified after the first dose, and 27 in a million cases after the second dose. A similar finding was made for the risk of pericarditis.
These risks are therefore extremely rare. Gold “Rare side effects are by definition too few to be visible in a clinical trial based on a sample of a few thousand people”, remember Romain Basmaci. “For example, you would have to have 3,000 patients in a clinical trial to have a 95% probability of detecting a rare adverse event that would occur once in a thousand”, calculates Mathieu Molimard, head of the pharmacology department of the Bordeaux University Hospital. In the case of myocarditis or pericarditis, the required sample should therefore number around a hundred thousand or even a million patients. He is “impossible to highlight” in the case of a clinical trial on a few thousand people, Romain Basmaci slice. Or even by increasing the number of clinical trials bringing together tens of thousands of patients.
This finding of a sample too small to identify a rare side effect does not mean that the clinical trial was poorly conducted. “A clinical trial is being done to prove that the drug is effective, that there are no common adverse events, and to estimate the frequency of these possible common adverse events, such as pain at the injection site, fever or body aches … That we know very quickly “, recalls Mathieu Molimard. “This is the medical standard, for all clinical trials, for all drugs “, confirms the pharmacologist.
There is only the “observational study” in “real life”, that is to say the follow-up of the large-scale vaccination campaign in the present case, which makes it possible to detect the undesirable effects occurring in the present case. a very low frequency, such as myocarditis or pericarditis. “As with any drug, long-term pharmacovigilance monitoring is necessary”, underlines Romain Basmaci, because “only pharmacovigilance can assess these risks.” This is how rare cases of thrombosis linked to the AstraZeneca vaccine were identified. “This is the normal and usual situation in the development of a drug or a vaccine”, reminds the pediatrician.
“The undesirable effects listed in adults or adolescents cannot, a priori, be extrapolated to the youngest”, warn however the learned societies of pediatrics and infectious pathology, recalling that “effects specific undesirable effects could be described according to age groups “. In 2009, thenarcolepsy has, for example, been observed mainly in children and adolescents as a secondary reaction to the Pandemrix vaccine against H1N1 influenza during pharmacovigilance, although it had not been demonstrated during clinical studies.
However, it will not be necessary to wait five years to find out whether the vaccine is responsible for myocarditis or pericarditis in children, assures Mathieu Molimard. “With the vaccination of children starting in the United States and Israel, we will quickly know the frequency of rare adverse events, explains the pharmacologist. We’ll find out by the end of the year, not five years from now. “ Washington has indeed authorized the vaccination of 5-11 year olds in early November. Some 28 million children are eligible and 900,000 have already received their first dose, according to the coordinator of the fight against the pandemic at the White House. In mid-November, the Hebrew state in turn gave the green light to the vaccination of this population. The date on which this vaccination campaign will begin, however, has not yet been announced by the Israeli authorities.
“Adverse vaccine events occur quickly in patients, within two months in most cases.”, affirms Mathieu Molimard. “Adverse events may be related to the product itself”, details the pharmacologist. This is the case, for example, with pain at the injection site. In that case, “they occur within 24 to 48 hours”. “Or they are linked to the activation of immunity”, continues the specialist. In that case, “They occur when the antibodies are at their maximum, they do not appear after five years.” And the expert concludes: “If you don’t have symptoms at two months, you won’t have any side effects from the vaccine.”
* These links refer to articles or content in the English language.