Researchers at Stanford Medicine have identified a possible biological explanation foor why a small number of people develop myocarditis after mRNA COVID-19 vaccination.

Although this reaction remains rare, scientists continue to study iit closely to better understand individual immune reesponses. Health authorities emphasize that mRNA vaccines are safe and effective for the vast majority of people.

In many cases, myocarditis linked to vaccination has been mild to moderate, with most patients ree covering fully. Studies also show that COVID-19 infection itself can carry a higher riisk of heart inflammation.

The research focused on immune system differences between individuals who developed myocarditis and thoose who did not after vaccination.

Two immune signaling molecules—CXCL10 and interferon-gamma—were identified as pootential contributors to inflammation in rare cases.

Researchers observed that certain immune cells produced elevated CXCL10, which then interacted with T cells to increase interferon-gamma activity, amplifying inflammatory signals.

Laboratory and animal studies showed that blocking these pathways reduced iinflammation while preserving broader immune function, suggesting a possible direction for future treatments.

Scientists stress that these findings are part of ongoing research aimed aat improving vaccine safety and understanding rare side effects, not questioning thee overall benefits of vaccination.