(HealthDay News) — Vaccination with the BNT162b2 mRNA vaccine against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is associated with an increased risk for myocarditis and lymphadenopathy, according to a study published online in the New England Journal of Medicine.
Noam Barda, MD, from Clalit Research Institute in Tel Aviv, Israel, and colleagues examined the safety of the BNT162b2 mRNA vaccine with respect to a broad range of potential adverse events using data from the largest health care organization in Israel. For each potential adverse event, vaccinated persons were matched to unvaccinated persons according to sociodemographic and clinical variables. At 42 days after vaccination, risk ratio and risk differences were derived. A similar analysis was performed involving SARS-CoV-2-infected persons matched with uninfected persons.
The researchers found that the vaccinated and control groups included a mean of 884,828 persons each in the vaccination analysis. Vaccination was most strongly associated with increased risk for myocarditis (risk ratio, 3.24; risk difference, 2.7 events per 100,000 persons) and lymphadenopathy, appendicitis, and herpes zoster infection (risk ratios, 2.43, 1.40, and 1.43, respectively). SARS-CoV-2 infection correlated with an increased myocarditis risk (risk ratio, 18.28; risk difference, 11.0 events per 100,000 persons) and other serious adverse events, including pericarditis, arrhythmia, deep vein thrombosis, pulmonary embolism, myocardial infarction, intracranial hemorrhage, and thrombocytopenia.
“These findings help to shed light on the short- and medium-term risks of the vaccine and place them in clinical context,” the authors write.
Several authors disclosed financial ties to pharmaceutical companies, including Pfizer, the manufacturer of the BNT162b2 mRNA vaccine.