Does a COVID mRNA booster raise myocarditis risk?
In England, myocarditis admissions rose mainly in males 16–39 within 0–6 days after mRNA doses (highest after dose 2); boosters still elevated risk but prior infection lowered vaccine-associated RIs.
Source
Risk of myocarditis and pericarditis after a COVID-19 mRNA vaccine booster and after COVID-19 in those with and without prior SARS-CoV-2 infection: A self-controlled case series analysis in England
What they did
Ran a nationwide self-controlled case series comparing admission risk windows after BNT162b2, mRNA-1273, and ChAdOx1-S doses and after SARS-CoV-2 infection, stratified by age, sex, dose, and prior infection.
What they found
2,284 myocarditis and 1,651 pericarditis admissions. Elevated vaccine RIs mainly in 16–39-year-olds 0–6 days post-dose, especially males. ChAdOx1-S elevation only after first dose (RI 5.23). Prior infection lowered second-dose RIs; infection itself raised risk over 1–27 days.
The limits
What it doesn't show
Hospital-admission SCCS estimates rare absolute risks incompletely for mild outpatient cases; does not weigh COVID benefits vs risks for individuals.
Key terms
- Self-controlled case series
- Method comparing incidence in risk windows vs control time within the same person.
- Relative incidence (RI)
- Ratio of event rate in post-exposure risk windows versus baseline windows.
- BNT162b2
- Pfizer-BioNTech COVID-19 mRNA vaccine.
- mRNA-1273
- Moderna COVID-19 mRNA vaccine (higher priming mRNA dose).
- ChAdOx1-S
- Oxford-AstraZeneca adenovirus-vectored COVID-19 vaccine.
- Booster dose
- Additional mRNA dose after a primary series; risk still elevated but generally lower than dose 2.
Flashcards
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Quiz yourself
Myocarditis admissions numbered about:
Common questions
How many myocarditis admissions?
2,284 (plus 1,651 pericarditis).
Who had elevated vaccine RIs?
Mainly 16–39-year-olds, especially males, 0–6 days postvaccination.
ChAdOx1-S pattern?
Elevated RI only after first dose (RI 5.23).
Effect of prior infection?
Lower vaccine-associated RIs than in infection-naive vaccinees.