Myocarditis after Covid-19 Vaccination in a Large Health Care Organization
Open accessAbstract
BACKGROUND: Reports have suggested an association between the development of myocarditis and the receipt of messenger RNA (mRNA) vaccines against coronavirus disease 2019 (Covid-19), but the frequency and severity of myocarditis after vaccination have not been extensively explored. METHODS: We searched the database of Clalit Health Services, the largest health care organization (HCO) in Israel, for diagnoses of myocarditis in patients who had received at least one dose of the BNT162b2 mRNA vaccine (Pfizer-BioNTech). The diagnosis of myocarditis was adjudicated by cardiologists using the case definition used by the Centers for Disease Control and Prevention. We abstracted the presentation, clinical course, and outcome from the patient's electronic health record. We performed a Kaplan-Meier analysis of the incidence of myocarditis up to 42 days after the first vaccine dose. RESULTS: Among more than 2.5 million vaccinated HCO members who were 16 years of age or older, 54 cases met the criteria for myocarditis. The estimated incidence per 100,000 persons who had received at least one dose of vaccine was 2.13 cases (95% confidence interval [CI], 1.56 to 2.70). The highest incidence of myocarditis (10.69 cases per 100,000 persons; 95% CI, 6.93 to 14.46) was reported in male patients between the ages of 16 and 29 years. A total of 76% of cases of myocarditis were described as mild and 22% as intermediate; 1 case was associated with cardiogenic shock. After a median follow-up of 83 days after the onset of myocarditis, 1 patient had been readmitted to the hospital, and 1 had died of an unknown cause after discharge. Of 14 patients who had left ventricular dysfunction on echocardiography during admission, 10 still had such dysfunction at the time of hospital discharge. Of these patients, 5 underwent subsequent testing that revealed normal heart function. CONCLUSIONS: Among patients in a large Israeli health care system who had received at least one dose of the BNT162b2 mRNA vaccine, the estimated incidence of myocarditis was 2.13 cases per 100,000 persons; the highest incidence was among male patients between the ages of 16 and 29 years. Most cases of myocarditis were mild or moderate in severity. (Funded by the Ivan and Francesca Berkowitz Family Living Laboratory Collaboration at Harvard Medical School and Clalit Research Institute.).
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In this study, troponin T was required to be elevated in all patients as part of the diagnostic criteria for myocarditis.
“In this study, troponin T was required to be elevated in all patients as part of the diagnostic criteria for myocarditis.”
From COVID-19, Myocarditis and Pericarditis (2023) · cites this paper as [89]
The Methods (Study Design and Data Collection; page unavailable) say patients qualified by meeting the CDC definition for suspected, probable, or confirmed myocarditis, not by a stated requirement for elevated troponin T. The Results (Patients and Clinical and Laboratory Findings; pages unavailable) report 54 qualifying cases but troponin T data for only 41, contrary to the claim that elevated troponin T was required in all patients. (LLM, conf=0.81)
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Experimental — accuracy not yet measuredIn 1 study from Israel, 81% of patients presented with chest pain, 2% with palpitations, 6% with dyspnea, 9% with fever, and 20% with pericardial effusion.
“In 1 study from Israel, 81% of patients presented with chest pain, 2% with palpitations, 6% with dyspnea, 9% with fever, and 20% with pericardial effusion. 89”
From COVID-19, Myocarditis and Pericarditis (2023) · cites this paper as [89]
The Results section (Clinical and Laboratory Findings; page unavailable) reports chest pain as the presenting symptom in 82% of cases, close to the cited 81%. Our copy does not substantiate the stated percentages for palpitations, dyspnea, fever, or pericardial effusion. (LLM, conf=0.88)
Experimental — accuracy not yet measured79% presented with abnormal electrocardiogram, while left ventricular ejection fraction was normal in 71% of patients; the majority presented with mild to moderate cardiac dysfunction.
“Seventy-nine percent presented with abnormal electrocardiogram, while the left ventricular ejection fraction was normal in 71% of patients; the majority of patients presented with mild to moderate cardiac dysfunction. 89”
From COVID-19, Myocarditis and Pericarditis (2023) · cites this paper as [89]
The Results (Clinical and Laboratory Findings) report normal ECGs in 8 of 38 patients, implying abnormal ECGs in 30 of 38 (79%). The Results (Echocardiography and Other Cardiac Imaging) report normal left ventricular function in 71% of patients with echocardiograms. The final clause overstates the finding: only 29% had any left ventricular dysfunction at presentation, although most of those cases were mild to moderate. (LLM, conf=0.90)
Experimental — accuracy not yet measuredThe BNT162b2 vaccine was associated with increased risk of myocarditis in Israeli participants, reaching a rate of approximately 3 events per 100,000 persons.
“However, the vaccine was associated with increased risk of myocarditis in Israeli participants, reaching a rate of approximately 3 events per 100,000 persons.398–400”
From Advances in COVID-19 mRNA vaccine development (2022) · cites this paper as [400]
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Cites
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- Authors
- Witberg, G., Barda, N., Hoss, S., Richter, I., Wiessman, M., Aviv, Y., Grinberg, T., Auster, O., Dagan, N., Balicer, R. D., & Kornowski, R.
- Affiliations
- Tel Aviv University (IL)
- Corresponding author
- Witberg, Guy
- Venue
- New England Journal of Medicine
- Publisher
- Massachusetts Medical Society
- Published
- 2021-12-02
- Volume
- 385
- Issue
- 23
- Pages
- 2132-2139
- ISSN
- 0028-4793 (ISSN-L)
- 1533-4406
- PMC
- PMC8531986
- OpenAlex
- W3202627533
- Cited by
- 613
- References
- 5
- Citations by year
- 2026: 28 · 2025: 31 · 2024: 83 · 2023: 137 · 2022: 297 · 2021: 37
- FWCI
- 92.85
- Type
- journal article
- Language
- en
- Open access
- green
- europepmc.org
- Locations
- New England Journal of Medicine (publishedVersion)
- Europe PMC (PubMed Central) (publishedVersion)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- Funders
- Clalit Health Services
- Topics
- Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › Viral Infections and Immunology Research
- Health Sciences › Medicine › Infectious Diseases › SARS-CoV-2 and COVID-19 Research
- Health Sciences › Medicine › Infectious Diseases › COVID-19 Clinical Research Studies
- Keywords
- myocarditis, COVID-19 vaccination, BNT162b2 mRNA vaccine, vaccine safety, incidence, young men, left ventricular dysfunction, cardiogenic shock, vaccine adverse events, Clalit Health Services, Israel, follow-up outcomes, echocardiographic follow-up, sex differences in adverse events
- MeSH terms
- COVID-19, BNT162 Vaccine, Adolescent, Adult, Delivery of Health Care, Echocardiography, Female, Hospitalization, Humans, Israel, Male, Middle Aged, Myocarditis, Retrospective Studies, Comorbidity, Incidence, Age Distribution, Sex Distribution, Ventricular Dysfunction, Left, Kaplan-Meier Estimate, Young Adult, Patient Acuity
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