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COVID-19 Vaccine Associated Myocarditis

During the experimental COVID-19 vaccines campaign, many vaccine recipients have suffered vaccine-associated myocarditis. There is a debate over the nature of the damage caused in these cases of myocarditis as well as the relative risk of myocarditis associated with SARS-CoV-2 infection or COVID-19 cases.

Myocarditis can be a challenging topic for a number of reasons, not the least of which is understanding the nature of case data, which sometimes does and sometimes does not include preclinical myocarditis, the severity of which may be different by kind.

Research

Increased occurrence of myocarditis, pericarditis and myopericarditis has been associated with Covid-19 inoculations,¹⁾ along with Covid-19 infection.

Incidence of Myocarditis Following the Second Dose of a Covid-19 mRNA Vaccine
	Age 12 - 17	Male Age 12-17	Age 18 - 24	Male Age 18-24	Male Age < 40	Rate from Sars-cov-2
Kaiser Permanente Study - Dec 27, 2021²⁾	1/1860	1/2650
Nature Medicine Paper - Dec 25, 2021³⁾	-	-	101 excess events per million (Moderna)	30 excess events per million
USA FDA ACIP Meeting Presentation⁴⁾		62.8 per million		50.5 per million

CDC Reports

17 May 2021–CDC's COVID-19 VaST Work Group Report ⁵⁾ – reported various presentations concerning myocarditis. VaST reported that cases seemed to occur:

predominantly in adolescents and young adults,
more often in males than females,
more often following dose 2 than dose 1, and
typically within 4 days after vaccination.

9 November 2021–CDC reported increased cases of myocarditis related to mRNA COVID-19 vaccinations from Pfizer-BioNTech and Moderna, “COVID Clinical Considerations: Myocarditis and Pericarditis after Receipt of mRNA COVID-19 Vaccines Among Adolescents and Young Adults.” The CDC continued to recommend use of these vaccinations while urging doctors to follow a list of clinical guidelines and to make VAERS reports as needed. ⁶⁾

In the December 31, 2020 MMWR the CDC released information related to COVID-19 vaccine safety in children aged 5–11 years, covering the November 3–December 19, 2021 period of slightly over a five weeks. The information was drawn from VEARS and VSAFE and was restricted to those who received Pfizer-BioNTech COVID-19 vaccine. ⁷⁾

Small Hong Kong Study

'Epidemiology of Acute Myocarditis/Pericarditis in Hong Kong Adolescents Following Comirnaty Vaccination' (Chua, Kwan et al., 2021)⁸⁾ “Conclusions: There is a significant increase in the risk of acute myocarditis/pericarditis following Comirnaty vaccination among Chinese male adolescents, especially after the second dose.”

Myocarditis Stratified by Age & Sex

Associate Professor Vinay Prasad wrote a Substack piece on December 26, 2021⁹⁾ that revisits the results of a paper that appeared in Nature Medicine called 'Risks of myocarditis, pericarditis, and cardiac arrhythmias associated with COVID-19 vaccination or SARS-CoV-2 infection' by Patone, Mei et al..¹⁰⁾ His analysis begins with the finding that the incidence of myocarditis in those under 40 years of age is higher post-vaccination than it is is post-Covid infection. It just gets worse from there.

Policy Considerations

In April, 2021, Israel was already warning about large numbers of cases of vaccine-associated myocarditis, a large portion of which were among young men.¹¹⁾

Pausing Moderna’s COVID Vaccine for Younger Age Groups

On October 6, 2021 Sweden and Denmark said they will pause the use of Moderna’s COVID vaccine for younger age groups after reports of side effects, including myocarditis and pericarditis. Following suit was Finland October 7, Iceland October 8 and France November 8.

France's decision to pause was supported by a study from the French National authority for Health (HAS). ¹²⁾ The HAS designed the study by taking cases of hospitalization of myo or pericarditis in inoculated people and matched them each to controls of similar age, sex & geography. They adjusted for history of myocarditis or pericarditis, history of SARS-CoV-2 infection etc. Essentially, they defined a signal (hospitalization for myo/peri within 7 days of inoculation of either Moderna or Pfizer) and compared it to a baseline (control of unvaxxed & uninfected).

What they found was for the second dose of Moderna for men under 30 (within 7 days of inoculation) an excess of hospitalization cases from myocarditis alone reaching ~131 per million doses. They also calculated an odds-adjusted ratio or OR (which is basically a multiple of the signal over baseline occurrence). 2-dose Moderna for men below 30 had an OR of ~80x (which is like saying 80x more risk vs. baseline) for myocarditis alone. For comparison SARS-CoV-2 infection in the previous month for myocarditis had a OR of ~7.9x.

Woman under 30 on the second dose of Moderna found an excess of 37 per million doses for myocarditis with an OR of ~40.6x. For Pfizer & myocarditis alone, men under 30 for the second doses found excess hospitalizations of 27 per million doses and an OR of ~10.9x, while woman saw an increase of 4 per million doses and an OR of ~11.4x.

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