Vaccination against Covid-19 increases risk of cardiac inflammation in male adolescents, study says

A study carried out in Thailand raises suspicions that mRNA vaccines against Covid-19 (such as Pfizer and Moderna) increase the signs of inflammation in the heart of male adolescents by about 2,000 times. Although previous research has already shown inflammation in the heart muscle or the lining of the heart (myopericarditis) as a side effect of vaccines and as a sequel to Covid itself 19, the most recent conclusion is that, among men, there is an age group in which vaccinal myopericarditis presents more risks than that acquired after natural infection by the coronavirus. The Thai study also points out that the risk is greater after the second dose.

Suspicions in this regard began to emerge in February 2021, with reports of heart inflammation after inoculation with Pfizer’s mRNA vaccine among Israeli military personnel. The first estimates, with considerable uncertainty, ranged from one case in 3.13 to one in 5.000. At the time, it was also suspected that the problem occurred especially after the second dose.

Months later, in June of last year, the professor of epidemiology and biostatistics at the University of California at San Francisco , Vinay Prasad, and four other physicians suggested to the US Centers for Disease Control and Prevention (CDC) six actions in response to these preliminary alarms, but they were ignored.

Among measures suggested were: give only one dose; exempt those previously infected from vaccination; give a second, more dilute dose; ban at least the Moderna vaccine, which is more concentrated than Pfizer’s, for the group; demand more evidence before giving the booster (third) dose to boys; immediately stop recommending doses for all adults who have had the Ômicron variant and have recovered, until specific studies are done in this group.

At the time, Rochelle Walensky, director of the CDC, said that “we did not see a sign and we intentionally looked for it in the more than 200 millions of doses we’ve given.” A similar attitude of waiving the risk, and sometimes making methodological choices that water down the problem (such as mixing teenagers with the elderly in analyses), was also seen by many authorities and commentators on the risk of blood clots in the case of Johnson & Johnson vaccines. Johnson (Janssen) and AstraZeneca/Oxford.

Prasad explains that resistance to the idea of ​​natural immunity (acquired after infection) has put more young men at risk, because for this group to catch the disease after two doses you have a greater risk of myocarditis than catching it after a single dose, at least when it comes to Moderna’s more concentrated vaccine. “The purpose of talking about myocarditis is not to criticize vaccines — which are a tremendous asset — but to take safety signals seriously so that we can customize age-appropriate vaccination strategies and maximize efficacy and minimize harm. ”, comments the expert. “This is introductory medicine.”

The US Food and Drug Administration (FDA), responsible for approving the vaccine, gave Pfizer up to 2024 to produce complete data on myocarditis after the second dose in young people aged five to 15 years, and up to December of 2022 to do the same for the third dose in the age group from 18 to


It is worth mentioning that the new vaccines for Covid-19, in different studies, are clearly less dangerous than the disease they seek to attenuate in different groups, especially the elderly. After the vaccination programs, drastic drops in the number of occupied hospital beds were observed, as well as drops in deaths caused by the coronavirus disease. In this sense, the debates based on the new research should encompass the need to update the risk-benefit analysis, in addition to reviewing mandatory vaccination so that adolescents can attend schools and universities.

Thai study

Although the sample of the study carried out in Thailand is not large – it was 200 girls and 202 boys, aged between 15 and years –, the major advantage of the research is the prospective methodology. That is, the scientists followed the young people in the long term, since before the second dose, monitoring different cardiac signals, both the electrical signals of the beats and the chemical signals in the blood. The study is a pioneer in the methodology applied to this problem, which has not been done by any of the major health agencies in the West.

As a result, 3% of the boys showed signs of inflammation in the muscle heart or the lining of the heart after the second dose. Previously, estimates for the incidence of this problem in this age group were 13 cases per one million complete vaccinations (with two doses) . The new estimate is therefore more than 2,000 times higher.

Only boys showed worrying cardiac signs after the second dose in the study. There were seven of them, and in four these signs were subclinical, that is, without manifestations more conducive to the attention of doctors, such as chest pain. Two were hospitalized. One was hospitalized with arrhythmia and was under observation.

Other results were already known from previous investigations: vaccine myopericarditis does not usually kill (no participant died), and hospitalization was required for a period of less than a week in two cases (average of 4.5 days).

The research has six authors associated with four institutions based in the capital Bangkok: the Bhumibol Adulyadej Hospital, the Department of Medicine Tropical Clinic at Mahidol University, the Department of Tropical Pathology at Mahidol University and Samitivej Srinakarin Hospital. Suyanee Mansanguan signs first authorship, Chayasin Mansanguan leads the study.

Cardiologists show concern

Anish Koka, a cardiologist in Philadelphia, says in his own publication that no expert would like to see his own child with the levels of cardiac inflammation in the blood observed in the Thailand study. “Given the theoretical risk of malignant cardiac arrhythmias, I would imagine that most cardiologists would follow the current guidelines for myocarditis and advise against intense cardiac activity for a few months,” he comments. “Sudden cardiac death in young athletes is obviously a dire complication that is very real, and it is likely that some portion of sudden cardiac death comes from subclinical myocarditis,” such as that seen in the four patients without chest pain in the study.

For Ellen Guimarães, a cardiologist and electrophysiologist who works in Goiânia, the Thai study is important because it is the first to carry out a series analysis of cardiac injury markers. These markers are substances released by the heart when it is damaged, such as troponin. The high level of troponin found in boys “is not a common finding”, the doctor told Gazeta do Povo. But she suggests caution: in relation to abnormalities in the measurements of electrical signals from the heart, “we have to watch ourselves, since the electrocardiogram of children and adolescents has peculiarities that are not truly abnormal changes”.

In any case, long-term follow-up is extremely important, as post-vaccination heart inflammation, even if mild, can generate scars in the heart muscle “which are a substrate for cardiac arrhythmias and sudden death”, Ellen warns.

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