A new argument in favor of vaccination for the American health authorities. The risk of myocarditis, an inflammation of the heart muscle, is increased for patients with Covid-19, according to a large American study (in English) of the Centers for Disease Prevention and Control (CDC), published Tuesday, August 31.
This risk of developing myocarditis was pointed out after the injection of the Covid-19 vaccines from Pfizer and Moderna, especially in boys and young men. But it is higher after infection with the disease itself, according to this new study, which analyzed data from consultations in more than 900 hospitals.
“Myocarditis remains rare in patients, with or without Covid-19, write the CDC. However, Covid-19 is a strong and important risk factor for myocarditis, this risk varying with age. “
Patients with Covid-19 between March 2020 and January 2021 were on average almost 16 times more likely to develop myocarditis than those who did not contract the virus, according to this study. This risk was more pronounced in people under the age of 16, as well as over the age of 50. In children, some cases of myocarditis identified may correspond to a pediatric multisystem inflammatory syndrome (PIMS or MIS-C), the study notes.
In 2020, the number of myocarditis consultations in these hospitals was 42% higher than in 2019 – the peaks corresponding to those in the number of Covid-19 cases. In addition, among people with both Covid-19 and myocarditis, the vast majority were diagnosed for both diseases in the same month. The exact mechanism that may be at the origin of this link is “unknown”, specify the CDC.
This study does not directly provide a point of comparison with the risk of myocarditis following vaccination. But CDC cites another Israeli study, published last week in the scientific journal NEJM. According to this, the risk of developing myocarditis after the injection of a messenger RNA vaccine (that of Pfizer) was multiplied by 3. And again according to this study, the risk of myocarditis associated with an infection by the coronavirus was as for him multiplied by 18 – that is to say much more than after a vaccination.