Myocarditis Cases Reported After mRNA-Based COVID-19 Vaccination in the US From December 2020 to August 2021 (25 January)
Vaccination against COVID-19 provides clear public health benefits, but vaccination also carries potential risks.
The risks and outcomes of myocarditis after COVID-19 vaccination are unclear.
To describe reports of myocarditis and the reporting rates after mRNA-based COVID-19 vaccination in the US.
Descriptive study
Reports of myocarditis to the Vaccine Adverse Event Reporting System (VAERS)
cdc.gov/vaccinesafety/ens...
After mRNA-based COVID-19 vaccine administration
Between December 2020 and August 2021 in
n = 192,405,448 older than 12 years of age in the US
During the analytic period
BNT162b2 vaccine, 12 years and older
mRNA-1273 vaccine, 18 years and over
Exposures
Vaccination with BNT162b2 (Pfizer-BioNTech) or mRNA-1273 (Moderna)
Main Outcomes and Measures
Expected rates of myocarditis by age and sex were calculated using 2017-2019 claims data.
For persons younger than 30 years of age, medical record reviews and clinician interviews were conducted to describe clinical presentation, diagnostic test results, treatment, and early outcomes.
Results
Among 192,405,448 persons
Receiving a total of 354,100,845 mRNA vaccines
1,991 reports of myocarditis to VAERS
1,626 met the case definition of myocarditis
Of those with myocarditis
Median age, 21 years (IQR, 16-31 years)
Median time to symptom onset, 2 days (IQR, 1-3 days)
Males
Comprised 82% of myocarditis cases
Reporting rates for cases of myocarditis.
Within 7 days after COVID-19 vaccination, exceeded the expected rates of myocarditis across multiple age and sex strata
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