The research suggests that mRNA vaccination can activate certain immune cells, which then communicate with other immune cells through inflammatory signaling. In laboratory and animal experiments, the resulting activity was associated with markers of heart injury.

The findings offer a possible explanation for part of the biological pathway involved in rare vaccine-associated myocarditis. However, research findings from laboratory models do not automatically translate into a treatment or prevention strategy for people.

What About Genistein?

The Stanford researchers also investigated genistein, a naturally occurring compound found in soy.

In their experiments, concentrated genistein preparations reduced some of the inflammatory effects associated with the pathway under investigation. However, the study does not establish that eating soy foods or taking a genistein supplement can prevent myocarditis in vaccinated people.

The researchers themselves described this as an area requiring further investigation. The experimental material was also more concentrated than typical dietary supplements, making it inappropriate to treat the findings as a recommendation for self-treatment.

Does This Mean the Vaccines Are Unsafe?

The available evidence does not support describing mRNA COVID-19 vaccines as broadly unsafe.

At the same time, it is important to acknowledge known risks honestly. Myocarditis and pericarditis are recognized rare adverse events, and U.S. regulators have required warnings about them in vaccine information. Safety monitoring is ongoing.

The CDC also notes that COVID-19 infection itself can cause myocarditis and other cardiovascular complications. When evaluating suspected myocarditis after vaccination, healthcare professionals are advised to consider recent COVID-19 infection and other possible causes as part of the medical assessment.