It’s no secret that some mRNA vaccines (messenger RNA) against covid-19 can cause myocarditis, i.e. inflammation in the heart muscle, as a rare adverse effect. Now, a team of scientists from Yale University, in the United States, discovers the reason for the unwanted effect and presents solutions to further reduce the risk.
Here, it is worth mentioning that myocarditis was only observed after immunization with Pfizer and Moderna formulas, both known to use mRNA technology. Data available from surveillance systems indicate that the rare adverse effect is more common in adolescents and young men (up to 20 years of age), in addition to being more common after the second dose.
Should men get the covid-19 vaccine?
Before we continue, it must be noted that the adverse effect is rare enough for the use of mRNA vaccines against covid-19 to be maintained. This means that, today, health authorities understand that the benefits of being immunized against the disease are greater than the potential risk of inflammation.
In fact, this analysis has already been carried out both by the Food and Drug Administration (FDA), in the USA, and by the National Health Surveillance Agency (Anvisa), in Brazil.
In the package leaflet for the Pfizer vaccine, available to all Brazilians on the Anvisa website, it is highlighted: “Generally, cases (of post-vaccination myocarditis in young men) are mild and individuals tend to recover within a short period of time. time after standard treatment and rest”.
What causes the rare adverse effect of the mRNA vaccine?
Published in scientific journal Science Immunology, the Yale study involved taking blood samples from 23 male patients who developed myocarditis or pericarditis after being vaccinated with the mRNA formulas. Participants were aged between 13 and 21 years.
The objective of the analyzes was to understand, in detail, the immunological response of the patients. Contrary to what was believed, the inflammation of the heart tissue was not caused by the attack from antibodies generated by the vaccine against the SASR-CoV-2 coronavirus. In fact, the damage was caused by the activation of a generalized immune response involving both immune and inflammatory cells.
“These individuals’ immune systems are overreacted and produce excessive cytokines (proteins) and cellular responses,” explains Carrie Lucas, an associate professor at Yale and one of the study’s authors, in a statement. Among the high production cells, the authors highlight T and NK defense cells, in addition to inflammatory monocytes.
To mitigate the risks, one of the strategies is to increase the interval between vaccines to at least eight weeks, suggests the research. Another point is that covid-19 itself can cause myocarditis. “I hope that this new discovery will allow us to further optimize mRNA vaccines, which, in addition to offering clear health benefits during the pandemic, have tremendous potential to save lives in numerous future applications”, adds Anis Barmada, another author of the study.
Source: Science Immunology, Yale University e Anvisa
