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Review 2: Surveillance of Myopericarditis following COVID-19 Booster Dose Vaccination in a Large Integrated Health System"

This preprint evaluates the risk of Myopericarditis associated with the Covid-19 booster. Reviewers found the study reliable and shows a low associated risk between Myopericarditis and the booster; however, this study lacks long-term follow-up or historical data comparison.

Published onMay 25, 2022
Review 2: Surveillance of Myopericarditis following COVID-19 Booster Dose Vaccination in a Large Integrated Health System"
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key-enterThis Pub is a Review of
Surveillance of Myopericarditis following COVID-19 Booster Dose Vaccination in a Large Integrated Health System

AbstractPurposeThe risk of myopericarditis following COVID-19 booster vaccination has not been extensively evaluated. We provide a timely case ascertainment of myocarditis following COVID-19 booster vaccine in individuals age 18-39 years from an integrated health system.MethodsWe studied a cohort of 65,785 Kaiser Permanente (KP) Northwest Health Plan members aged 18-39 years who received a COVID-19 vaccine booster at least 5 months following completion of the primary series. We identified cases of myopericarditis by searching the electronic health record for the National Center for Health Statistics (NCHS) text label for ‘myocarditis’ or ‘pericarditis’ diagnosis codes in all inpatient and outpatient encounters through January 18th 2022. The cohort was followed for 21 days after their booster. We excluded anyone with a documented diagnosis of myocarditis or pericarditis before their first COVID-19 vaccination. Two physicians independently reviewed the identified patient records and applied the CDC myocarditis and pericarditis surveillance case definition to classify records as confirmed, probable or excluded based on the prior published definition.ResultsOur method identified 6 patients who met the confirmed or probable CDC case definition for acute myocarditis or pericarditis within 21 days of COVID-19 booster dose among 65,785 eligible members. Four cases occurred in 27,253 men. Overall, we estimated 9.1 cases (exact 95% CI 3.4 to 19.9) of post-booster myopericarditis per 100,000 booster doses given. In men, we estimated 14.7 cases (exact 95% CI 4.0 to 37.6) per 100,000 booster doses given.ConclusionWe identified a rate of 9.1 cases of myopericarditis per 100,000 COVID-19 booster doses which is higher than prior estimates reported by the Vaccine Adverse Event Reporting System (VAERS). Myopericarditis occurs following COVID-19 booster vaccine and may be underreported by current surveillance methods. High sensitivity of these case estimates is essential when modeling risk and benefit for sequential COVID-19 vaccinations for the general population.

RR:C19 Evidence Scale rating by reviewer:

  • Reliable. The main study claims are generally justified by its methods and data. The results and conclusions are likely to be similar to the hypothetical ideal study. There are some minor caveats or limitations, but they would/do not change the major claims of the study. The study provides sufficient strength of evidence on its own that its main claims should be considered actionable, with some room for future revision.


The present manuscript examines the incidence of myocarditis and pericarditis after COVID-19 booster vaccination in 65,785 individuals 18-39 years old from the Kaiser Permanente Northwest Plan using diagnosis codes. Cases were reviewed by 2 physicians (cardiologists?). Overall, 6 patients met the criteria for myopericarditis within 21 days of a booster vaccination with 34 cases occurring in men. They estimate 14.7 cases per 100,00 poster doses given which are higher than previous estimates using the VAERS registry. All
received the Pfizer vaccine/. 5/6 developed CP within 4 days of vaccination. Of note, one patient had J&J followed by Pfizer. Although interesting, these data simply confirm a rather low incidence of this type of event occurring after booster vaccination with most having normal heart function by the echo. However, there was no follow-up provided. None of the cases understand biopsy to prove myocarditis.

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