- Myocarditis and pericarditis are caused, most of the time, by a viral infection such as Covid-19.
- These infections tend to affect young men.
74.9% of the 5,023,773 adolescents aged 12 to 17 in France are fully vaccinated according to health insurance. They have been entitled to the serum since June 15. But according to a study published in the journal European Heart Journal Quality of Care and Clinical Outcomes, some cases of myocarditis or pericarditis have been reported in this age group. Boys would be more concerned, especially after the second dose.
Inflammation of the heart muscle
Myocarditis is inflammation of the heart muscle while pericarditis is inflammation of the membrane that surrounds the heart. To arrive at their results, the researchers analyzed reports of adverse reactions after the first or second dose of the messenger RNA vaccine, Pfizer and Moderna. These came from the global pharmacovigilance database and mainly from European countries, including France, Germany, Spain, Italy and the United Kingdom. “We looked more specifically at the declarations of myocarditis and pericarditis which seemed to be more frequent in young people.”, explains Dr François Montastruc, pharmacologist at the pharmacovigilance center of Toulouse University Hospital and main author of the study.
Five times more risk in the second dose
In all, 4,942 reports concerned adolescents, including 242 for cases of myocarditis or pericarditis. In detail, the latter were hospitalized in eight out of ten cases. The first symptoms usually appear four days after the first dose and three days after the second. Thus, researchers estimate the risk of side effects five times higher during the second dose and ten times greater in boys than in girls, regardless of the dose.
“This study brings additional elements to the discussions around the vaccine regimens used, in particular in young male adolescents, underlines Dr François Montastruc. Thus, some countries have recommended the realization of a single dose in this population such as England, others a spacing of doses. Research must continue to try to answer these questions on solid scientific grounds. In all cases, our results in no way call into question the interest and the benefit / risk ratio of vaccination even in these populations, which has already been demonstrated in large multicenter randomized studies.”.
Risks for all age groups
In other age groups, cases of myocarditis or pericarditis have also been recorded after vaccination or after infection with Covid-19. Indeed, according to National Agency for Medicines and Health Products Safety (ANSM), there is an uncommon risk of one of these two infections within seven days of vaccination against Covid-19 with an mRNA vaccine, Pfizer or Moderna, in subjects aged 12 to 50 years in France and more particularly among young people from 12 to 29 years old. The authority nevertheless emphasizes that the condition of these patients is generally improving and that no deaths have been reported.