New insights into post-vaccine heart inflammation cases

When new COVID-19 vaccines were first administered two years ago, public health officials found an increase in cases of myocarditis, an inflammation of the heart muscle, particularly among young males who had been vaccinated with mRNA vaccines. It was unclear, however, what exactly was causing this reaction. In a new study, Yale scientists have identified the immune signature of these heart inflammation cases.

These findings rule out some of the theorized causes of heart inflammation and suggest potential ways to further reduce the incidence of a still rare side effect of vaccination, the authors say.

The increased incidence of myocarditis during vaccination was seen primarily in males in their teens or early 20s, who had been vaccinated with mRNA vaccines, which are designed to elicit immune responses specifically to the SARS-CoV-2 virus.

According to the CDC, among males aged 12 to 17, about 22 to 36 per 100,000 experienced myocarditis within 21 days after receiving a second vaccine dose. Among unvaccinated males in this age group, the incidence of myocarditis was 50.1 to 64.9 cases per 100,000 after infection with the COVID-19 virus.

For the new study, the Yale research team conducted a detailed analysis of immune system responses in those rare cases of myocarditis among vaccinated individuals. They found that the heart inflammation was not caused by antibodies created by the vaccine, but rather by a more generalized response involving immune cells and inflammation.

Reference:

Cytokinopathy with aberrant cytotoxic lymphocytes and pro-fibrotic myeloid response in SARS-CoV-2 mRNA vaccine-associated myocarditis,Science Immunology, DOI 10.1126/sciimmunol.adh3455