Slight Increased Risk for Carditis After BNT162b2 Vaccine Administration

Following reports of carditis associated with COVID-19 vaccination, researchers compared BNT162b2 and CoronaVac to determine their effect on risk for the condition.

An increased risk for carditis may be associated with the BNT162b2 COVID-19 vaccine from Pfizer-BioNTech, according to research published in the Annals of Internal Medicine.

For the study, researchers sourced data from the Hospital Authority of Hong Kong, which includes population-based vaccination records from the Department of Health that were linked with electronic medical records from the region. Inpatients with new-onset carditis (n=160) and matched noncarditis inpatients (n=1533) were assessed for whether they received the BNT162b2 or CoronaVac (Sinovac) vaccine for COVID-19, up to August 2021.

During the study period, there had been 3,496,629 doses of BNT162b2 and 2,291,444 doses of CoronaVac administered in the Hong Kong region.

Cases and controls were 62.5% and 61.6% men; had a mean age of 57.48 (standard deviation [SD], 24.23) and 58.38 (SD, 23.78) years; 48.8% and 56.1% were using cardiovascular medications; 36.2% and 39.7% had hypertension; 12.5% and 8.0% had heart failure; 12.5% and 4.2% received the BNT162b2 COVID-19 vaccine; and 4.4% and 3.9% received the CoronaVac COVID-19 vaccine, respectively.

The cumulative incidence of carditis following vaccination was 0.57 per 100,000 doses and 0.31 per 100,000 doses after the BNT162b2 and CoronaVac vaccines, respectively.

In a multivariate conditional logistic regression analysis, risk for carditis was associated with BNT162b2 vaccination (adjusted odds ratio [aOR], 3.57; 95% CI, 1.93-6.60). Stratified by gender, the increased risk was observed among men and boys (aOR, 4.68; 95% CI, 2.25-9.71) and not among women and girls (aOR, 2.22; 95% CI, 0.57-8.69). Stratified by age, risk for carditis was more pronounced among adolescents (aged 12-17 years; aOR, 13.79; 95% CI, 2.86-110.38) than among adults (aOR, 2.41; 95% CI, 1.18-4.90).

In sensitivity analyses, which removed individuals with COVID-19, stratified by dose and by myocarditis and pericarditis diagnoses, the data indicated that pericarditis risk was not associated with the BNT162b2 vaccination (aOR, 1.06; 95% CI, 0.35-3.22).

This study was limited by the sample size for the subset of adolescent inpatients, in which there was insufficient data for the logistic regression, resulting in wide confidence intervals.

”We observed an increased risk for carditis associated with the use of BNT162b2, particularly in young male persons receiving the second dose,” the study authors wrote. “Although the absolute risk is very low, this elevated risk should be made known to vaccine recipients and physicians and be weighed against the benefits of vaccination.”

Disclosure: Multiple authors declared affiliations with industry. Please refer to the original article for a full list of disclosures.


Lai FTT, Li X, Peng K, et al. Carditis after COVID-19 vaccination with a messenger RNA vaccine and an inactivated virus vaccine: A case–control study. Ann Intern Med. Published online January 25, 2022. doi:10.7326/M21-3700