The US Food and Drug Administration has asked two makers of mRNA vaccines to broaden their age range for warning young men about rare side effects that cause heart inflammation. The letters, reported by CBS News, request updates to safety information based on new studies linking the reactions to vaccination.
Currently, Moderna’s label warns young men aged 18-24, while Pfizer says 12-17 years old. The FDA is now seeking to expand this range to 16-25 years old and cite a 2024 paper funded by the agency in their product information. Research has shown that myocarditis and pericarditis are driven by an immune system response triggered by inflammatory proteins.
Myocarditis causes fatigue and shortness of breath, while pericarditis leads to chest pain. A 2022 study found additional 22 cases of myocarditis for every million 18-29 year olds vaccinated with Pfizer, and 31 cases per million for Moderna vaccines.
However, cardiologist Steven Nissen emphasizes that public health is harmed by over-emphasis on rare vaccine side effects compared to the risk of Covid itself. “You’re much more likely to die from Covid than myocarditis,” he said.
Vaccine-associated myocarditis cases have decreased since the initial vaccine rollout, possibly due to fewer booster shots. In Canada, rates were lower in vaccinated individuals compared to the US, where the first two mRNA doses were given more quickly.
Source: https://www.statnews.com/2025/05/22/fda-moderna-pfizer-biontech-mrna-covid-vaccine-myocarditis-heart