Stanford (Calif.) Medicine researchers have identified the immune cell process behind a rare COVID-19 vaccine reaction, myocarditis.
A two-step immune cell sequence after vaccination triggers “inflammatory activity,” which results in direct injury to heart muscles, according to a study published Dec. 10 in Science Translational Medicine.
While a myocarditis reaction associated with mRNA-based COVID-19 vaccines is “rare but real,” a case of COVID-19 is about “10 times as likely to induce myocarditis as an mRNA-based COVID-19 vaccination,” according to a Dec. 10 Stanford Medicine news release.
Vaccine-associated myocarditis occurs in about 1 in every 140,000 vaccinations after a first dose and 32,000 after a second dose. Incidence is highest among men age 30 or younger, at 1 in 16,750 vaccinations. Most cases result in full heart function retained or restored.
“The mRNA vaccines have done a tremendous job mitigating the COVID pandemic,” Joseph Wu, MD, PhD, director of the Stanford Cardiovascular Institute and study author, said in the release. “Without these vaccines, more people would have gotten sick, more people would have had severe effects and more people would have died.”
Read the full study here.
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