U.K and U.S public health officials claim cases of myocarditis and pericarditis following Covid-19 vaccination are rare — but new research published online in the Journal of American Medical Association (JAMA) shows they may happen more often than reported.
Post-vaccine myocarditis and pericarditis also appear to represent two “distinct syndromes,” Dr. George Diaz, with the Providence Regional Medical Center Everett, told Medscape Cardiology.
Diaz and colleagues reviewed 2,000,287 electronic medical records (EMR) of people who received at least one Covid-19 vaccination.
The records, obtained from 40 hospitals in Washington, Oregon, Montana and California, showed 20 people had vaccine-related myocarditis (1.0 per 100,000) and 37 had pericarditis (1.8 per 100,000).
A recent report, by the Centers for Disease Control and Prevention (CDC), based on data from the Vaccine Adverse Events Reporting System (VAERS), suggested an incidence of myocarditis of about 4.8 cases per 1 million following receipt of an mRNA COVID vaccine.
The median age of the CDC report’s cohort was 57 years, and 59% were women. Only 77% received more than one dose. Fifty-three percent received Pfizer, 44% Moderna and 3% received Johnson & Johnson’s (J&J) COVID vaccine.
Myocarditis is inflammation of the heart muscle that can lead to cardiac arrhythmia and death. According to researchers at the National Organisation for Rare Disorders, myocarditis can result from infections, but “more commonly the myocarditis is a result of the body’s immune reaction to the initial heart damage.”
Pericarditis is often used interchangeably with myocarditis and refers to inflammation of the pericardium, the thin sac surrounding the heart.
The new JAMA study showed a “similar pattern [to the CDC study], although at higher incidence [of myocarditis and pericarditis] after vaccination, suggesting vaccine adverse event under-reporting.”
The JAMA report also stated: “Additionally, pericarditis may be more common than myocarditis among older patients.”
“Our study resulted in higher numbers of cases probably because we searched the EMR, and [also because] VAERS requires doctors to report suspected cases voluntarily,” Diaz told Medscape. Also, in the governments’ statistics, pericarditis and myocarditis were “lumped together,” Diaz said.