the staff of the Ridgewood blog
Ridgewood NJ, the Pfizer-BioNTech SARS-CoV-2 vaccine is associated with an increased risk of myocarditis (inflammation of the heart muscle), but infection with the virus is associated with a much greater risk of the condition, according to a real-world case-control study published on August 25 in the New England Journal of Medicine. Researchers analyzed the health records of more than 2 million people who are members of the Clalit Health Services (CHS), the largest healthcare organization in Israel. Vaccination was associated with a 3-fold increase in the risk of myocarditis (risk ratio [RR], 3.24, 95% confidence interval [CI], 1.55-12.44), as well as several other conditions including swollen lymph nodes (RR, 2.43; 95% CI, 2.05 to 2.78), appendicitis (RR, 1.40; 95% CI, 1.02 to 2.01), and herpes zoster infection (RR, 1.43; 95% CI, 1.20 to 1.73).
In a separate cohort, the researchers found SARS-CoV-2 infection is associated with an 18-fold increased risk of myocarditis (RR, 18.28; 95% CI, 3.95 to 25.12), as well as an increased risk of several other serious adverse events such as pericarditis (inflammation of tissue surrounding the heart), irregular heartbeat, blood clots, heart attack, bleeding in the brain, and kidney damage. Pfizer-BioNTech and the US CDC are conducting studies to examine the risks of myocarditis and pericarditis among people who receive the vaccine.