Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Oct 15:365:41-43.
doi: 10.1016/j.ijcard.2022.07.031. Epub 2022 Jul 21.

Acute myocarditis following a third dose of COVID-19 mRNA vaccination in adults

Anthony Simone  1 , John Herald  1 , Aiyu Chen  2 , Rohith Nayak  1 , Yuh-Jer Albert Shen  1 , Ming-Sum Lee  3
Affiliations

Acute myocarditis following a third dose of COVID-19 mRNA vaccination in adults

Anthony Simone et al. Int J Cardiol. .

Abstract

Introduction: Myocarditis has been reported following the second dose of COVID-19 mRNA vaccination. Whether administration of additional doses of COVID-19 vaccines further increases the risk of myocarditis is unknown.

Methods: We included individuals who received one to three doses of BNT162b2 or mRNA-1273 mRNA vaccine between 12/14/2020 and 2/18/2022. Myocarditis within 21 days of vaccine administration was identified using electronic medical records. Incidence rate ratios were calculated by comparing the observed incidence with the expected incidence from the same population during a 365-day baseline period.

Results: Of 3,076,660 KPSC members who received at least one dose of COVID-19 mRNA vaccines, 2,916,739 (94.5%) received at least two doses, and 1,146,254 (47.0%) received three doses. The incidence rate ratio for myocarditis was 0.86 (95% CI 0.31-1.93) for the first dose, 4.22 (95% CI 2.63-6.53) for the second dose, and 2.61 (1.13-5.29) for the third dose. Most myocarditis cases following the second and third dose occurred within seven days of vaccination.

Conclusion: Myocarditis was a rare event observed after the second or third dose of vaccination. Most cases presented within seven days of vaccination. The incidence of myocarditis following the third dose was not significantly higher than that observed after the second dose.

Keywords: Adverse event; Booster; COVID-19; Hospitalization; Myocarditis; Third-dose; Vaccination.

PubMed Disclaimer

Conflict of interest statement

None.

References

    1. Andrews N., Tessier E., Stowe J., Gower C., Kirsebom F., Simmons R., et al. Duration of protection against mild and severe disease by Covid-19 vaccines. N. Engl. J. Med. 2022;386:340–350. - PMC - PubMed
    1. Bar-On Y.M., Goldberg Y., Mandel M., Bodenheimer O., Freedman L., Kalkstein N., et al. Protection of BNT162b2 vaccine booster against Covid-19 in Israel. N. Engl. J. Med. 2021;385:1393–1400. - PMC - PubMed
    1. Magen O., Waxman J.G., Makov-Assif M., Vered R., Dicker D., Hernan M.A., et al. Fourth dose of BNT162b2 mRNA Covid-19 vaccine in a nationwide setting. N. Engl. J. Med. 2022;386(17):1603–1614. - PMC - PubMed
    1. Oster M.E., Shay D.K., Su J.R., Gee J., Creech C.B., Broder K.R., et al. Myocarditis cases reported after mRNA-based COVID-19 vaccination in the US from December 2020 to august 2021. JAMA. 2022;327:331–340. - PMC - PubMed
    1. Simone A., Herald J., Chen A., Gulati N., Shen A.Y., Lewin B., et al. Acute myocarditis following COVID-19 mRNA vaccination in adults aged 18 years or older. JAMA Intern. Med. 2021;181:1668–1670. - PMC - PubMed