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Review 1: "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 1: "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.


COVID-19 has been a major disaster for mankind, with deaths surpassing wars. The efficacy of mRNA vaccines against the original SARS-CoV-2 virus was excellent and seemed to overcome COVID-19. The pathogen SARS-CoV-2 is an RNA virus, and as expected, mutations in the virus occurred at a high frequency, resulting in alpha, beta, and delta variants of concern (VOC), but the vaccine was effective against these mutant VOCs as well. However, the efficacy of mRNA vaccines against Omicron VOCs with many mutations is limited, and while they may be effective in preventing severe disease, they are not very effective in stopping infection. In this context, vaccine adverse reactions come into close focus and myopericarditis is one of the most important reactions except anaphylaxis.

The authors followed 65,785 third-time vaccinees of Kaiser Permanente (KP) Northwest Health Plan members aged 18-39 years until 21 days after vaccination and identified 6 individuals who met the Center for Disease Control (CDC) myocarditis and pericarditis surveillance case definition (9.1 per 100,000). Four of 27,253 males (14.7 per 100,000) and two of 38,532 females (5.2 per 100,000) were confirmed. The male risk was higher than that of myopericarditis following booster dose in Israel men aged 20-24 (4.7 per 100,000).

Myopericarditis reported in the Vaccine Adverse Event Reporting System (VAERS) was 0.2 per 100,000 doses, much lower than the current study results and likely an underreporting. The annual incidence of myopericarditis prior to COVID-19 was 6.1 in men and 4.4 in women, and even using 21 days as the observation period, the vaccine is calculated to increase the risk by 42.0 and 20.8 times, respectively.

If possible, it would be desirable to add a comparison with historical data on the incidence of myopericarditis in the same district and whether it is similarly high in other districts.

Recently, the sequelae, as well as complications of COVID-19, have become a major problem (Long COVID). Some of those who recovered from COVID-19 showed slight cardiac dysfunction with a slight elevation of cardiac troponin and inflammation. Myopericarditis due to COVID-19 or vaccination may progress to dilated cardiomyopathy. Although booster vaccination greatly increases antibody titers and cellular immunity, the results of this study will provide information for considering the merits and demerits of a third vaccination against the Omicron VOCs in the future. Unfortunately, the fourth dose of the COVID vaccine offers only a slight boost against Omicron VOC infection (medRxiv (2022) and medRxiv (2022).). These studies clearly show the need for new vaccines without severe adverse reactions, which can prevent infection with emerging VOCs.

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