Researchers studying mRNA COVID-19 vaccines say they have identified a “possible biological mechanism” that could help explain the rare myocarditis cases seen mostly in younger males after vaccination. While these cases remain uncommon, scientists have been working to understand why they happen.

A Stanford Medicine–related study points to immune signaling proteins called “CXCL10 and IFN-gamma” as possible triggers. Researchers found these proteins may activate inflammatory responses that, in rare situations, could affect heart tissue.

In laboratory and animal testing, immune cells exposed to vaccine components produced these signals, which were “linked to inflammation that could affect heart tissue.” This gives scientists a clearer idea of how myocarditis might develop after vaccination in a small number of people.

The researchers stressed that “the overall risk remains very low.” They also noted that COVID-19 infection itself carries a greater risk of myocarditis and other serious complications than vaccination does, reinforcing that vaccines remain broadly safe and effective.

The study also found that blocking these inflammatory signals reduced “heart-related damage” in experiments without stopping the body’s wider immune response. Compounds like “genistein showed some protective effects,” but scientists caution this is still early research and “not an immediate treatment recommendation.” More studies are needed to confirm whether these findings could lead to future prevention strategies.