EEvery medical procedure has both benefits and risks. When it comes to vaccinations, the benefits far outweigh the potential risks for most people.
The new COVID-19 vaccines based on mRNA technology are no exception. But one risk associated with them – myocarditis, especially in young men – has raised public concern.
A new study published in JAMA has found that the risk of developing myocarditis – an inflammation of the heart muscle often triggered by the immune system in response to infection – shortly after receiving the COVID-19 vaccination is lower than the risk that may arise from the disease itself.
Read more: The best way to treat insomnia
Researchers led by Dr. Mahmoud Zureik, professor of epidemiology and public health at the University of Versailles, studied people aged 12 to 49 who were hospitalized with myocarditis in France between December 2020 and June 2022, when mass vaccination campaigns were taking place. They divided people into three groups: people who developed myocarditis and were hospitalized within seven days of an mRNA vaccine, people who were hospitalized within 30 days of COVID-19 illness but had not received an mRNA vaccine in the previous seven days, or people who had myocarditis that was caused by other causes. All were followed for 18 months.
During this period, people with vaccine-related myocarditis were half as likely to be readmitted to hospital for myocarditis or heart-related events as people with infection-related myocarditis or people with myocarditis due to other causes.
The results suggest that the risk of myocarditis associated with the mRNA vaccines is “very, very small,” Zureik says. And it’s important to remember that the risk of COVID-19 to the heart “is not limited to myocarditis. There are other cardiovascular risks as well.”
Read more: Long COVID looks different in children
The findings come at a timely pace as the number of COVID-19 cases and emergency room visits in the U.S. continues to rise. The increase is due in part to new variants and people’s waning immunity from their last vaccinations, which targeted different versions of SARS-CoV-2. As a result, the U.S. Food and Drug Administration recently authorized an updated version of the vaccine to account for the variants currently circulating. However, uptake of recent vaccinations has been low.
The study did not go into detail about why the vaccines are associated, even slightly, with myocarditis or why the immune system’s response to the vaccine appears to be different than it is to COVID-19 infection. It’s possible that people who are hospitalized for that condition after vaccination may have milder courses because of awareness of the vaccine’s potential myocarditis risk, Zureik says.
More research is needed to better understand how the mRNA vaccines interact with the body’s immune system, but the results suggest that the vaccinations do not appear to be associated with a significantly higher risk of heart inflammation, even months after immunization.
