Multinational pharmacovigilance reports, health system surveillance studies and case series suggest an association between SARS-CoV-2 vaccination and myocarditis and pericarditis, which was more pronounced after the second dose of mRNA vaccines BNT162b2 and mRNA-1273. Severe myocarditis or pericarditis can lead to chronic heart failure or even death, and the harm to health cannot be ignored.
On June 25, 2021, based on the adverse event report released by the US Centers for Disease Control and Prevention (CDC), the FDA revised the Pfizer and Moderna COVID-19 mRNA vaccine instructions to warn the public that the above two COVID-19 vaccinations will increase the risk of myocarditis and pericarditis (inflammation of pericarditis).
In December 2021, according to a study of nearly 5 million Danish populations published by the BMJ, mRNA-1273 vaccination was associated with a significantly increased risk of myocarditis or pericarditis in groups aged 12 to 39 years, but the absolute incidence after vaccination was low, while the increased risk of developing such disease in women was significantly associated with BNT162b2 vaccination [1]. Led by Anders Husby of Imperial College London, the study analyzed the association between SARS-CoV-2 vaccination and myocarditis and pericarditis by collecting vaccination registration data from Across Denmark.
In this regard, the WHO and the European Medicines Agency have stated that considering that vaccines can prevent severe COVID-19 and reduce mortality, the benefits of vaccination outweigh the risks. On February 9, the American College of Cardiology publicly stated that while vaccine-associated myocarditis is a real side effect of mRNA vaccination, the benefits of vaccination still outweigh the risks given the small number of cases [2].
JAMA Cardiology: 16-24 years old
Young men are at highest risk of getting the mRNA vaccine
Previous case reports and surveillance data from the United States, Israel, and Canada suggest an increased risk of myocarditis after SARS-CoV-2 mRNA vaccination, higher after the second dose, and a more pronounced association in young men. Data from Canada and France suggest that there are more cases of myocarditis after mRNA-1273 than after BNT162b2 vaccination, but the specifics remain to be clarified.
JAMA Cardiology recently released a cohort study titled "SARS-CoV-2 Vaccination and Myocarditis in a Nordic Cohort Study of 23 Million Residents." The study, which enrolled 23.1 million residents from four Nordic countries of Denmark, Finland, Norway and Sweden, found that young men aged 16-24 years had the highest risk of developing myocarditis after receiving the second dose of the same vaccine for individuals receiving two doses of the same vaccine.
Figure 1 Research results (Source: [3])
Currently, the European Medicines Agency and the European Commission have approved four vaccines against SARS-CoV-2 – BNT162b2 (Pfizer-BioNTech), mRNA-1273 (Moderna), AZD1222 (AstraZeneca) and Ad26.COV2.S (Janssen). The Nordic countries mainly use BNT162b2 and mRNA-1273, two mRNA vaccines, of which the number of people vaccinated in the Nordic countries BNT162b2 is about 6 times that of mRNA-1273.
From December 27, 2020 to October 5, 2021, the researchers followed 23122522 residents over the age of 12 (49.8% of men and 50.2% of women) from four Nordic countries. By the end of the follow-up, the vaccination data were as follows:
▼There are 1238004 people in the 12-15 age group, and 487751 (39%) have received at least one dose of the SARS-CoV-2 vaccine;
▼There are 2675558 people in the 16-24 age group, and 2009995 (75%) have received at least one dose of THE SARS-CoV-2 vaccine;
▼There are 5046164 people in the 25-39 age group, and 3736517 (74%) have received at least 1 dose of the SARS-CoV-2 vaccine;
The researchers used Poisson regression to estimate the number of events to have a 95% CI incidence ratio (IRR) to compare the incidence of post-vaccination risk periods with those of the unoculated period. The results found that the risk of developing myocarditis within 28 days of BNT162b2 and mRNA-1273 was higher than that of the first dose of vaccine compared with those who did not; the risk after the second dose of mRNA-1273 was more pronounced than the risk after the second dose of BNT162b2, and the risk was highest among men aged 16 to 24 years. The specific data are as follows:
One
Incidence of myocarditis and pericarditis during the follow-up period
During the 28-day risk period (total 13 million person-years) after vaccination and vaccination, the researchers observed a total of 1077 cases of myocarditis and 1149 cases of pericarditis;
During the period of no vaccination, the incidence of myocarditis was 9.7 per 100,000 person-years in men and 4.3 per 100,000 person-years in women. In people aged 16 to 24 years, the incidence is 18.8 per 100,000 person-years for men and 4.4 per 100,000 person-years for women. The incidence of pericarditis increases with age, i.e. the risk of developing myocarditis is highest in older people. After vaccination, the risk of developing myocarditis is highest in younger people.
Year of 10,000 people: A statistical unit of data
Two
During the risk period, vaccination was associated with the onset of myocarditis
During the 28-day risk period after vaccination, the researchers observed 105 and 115 cases of myocarditis after the first and second doses of BNT162b2, respectively, and 15 and 60 cases of myocarditis after the first and second doses of mRNA-1273, respectively;
In young men aged 16 to 24 years, the second dose of BNT162b2 was a second dose of myocarditis with an adjusted IRR of 5.31 (95% CI, 3.68-7.68) and a second dose of mRNA-1273 with an adjusted IRR of 13.83 (95% CI, 8.08-23.68). Young men have lower yields on vaccination relative to women (Figure 2);
After comparing IRR data across age groups, the researchers found that young men aged 16 to 24 years who received the BNT162b2 and mRNA-1273 vaccines had a higher risk of developing myocarditis and a higher risk of the second dose than the first dose.
Three
During the risk period, vaccination is associated with the onset of pericarditis
During the 28-day risk period, a total of 7.39 pericarditis events occurred per 100,000 vaccinated men aged 16 to 24 years after receiving a second dose of mRNA-1273. The pattern of occurrence of male pericarditis is similar to that found in myocarditis, but the overall IRR is low; pericarditis is rare in women aged 12 to 39 years.
Fig. 2 Data on the incidence of myocarditis or pericarditis by sex and age within 28 days of vaccination (Source: [3])
The above studies show that the incidence of cardiac myositis and pericarditis is higher 28 days after receiving the SARS-CoV-2 mRNA vaccine compared with the unvaccinated SARS-CoV-2 mRNA vaccine. The risk of developing myocarditis and pericarditis is highest in the first 7 days of vaccination and is more pronounced after the second dose. The second dose of mRNA-1273 has the highest risk of developing myocarditis and pericarditis, and the risk is highest in young men aged 16 to 24 years.
Source: [4], for academic exchange only.
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Resources:
[1] Husby A, Hansen JV, Fosb l E, et al. SARS-CoV-2 vaccination and myocarditis or myopericarditis: population based cohort study[J]. British Medical Journal,2021,375:e068665.
[2]https://www.acc.org/Latest-in-Cardiology/Articles/2022/02/09/12/56/Vaccine-Associated-Myocarditis-Risk-in-Context
[3] Karlstad , Hovi P, Husby A, et al. SARS-CoV-2 Vaccination and Myocarditis in a Nordic Cohort Study of 23 Million Residents. JAMA Cardiol. 2022 Apr 20. doi: 10.1001/jamacardio.2022.0583. Epub ahead of print. PMID: 35442390.
[4]https://healthcare.utah.edu/healthfeed/postings/2022/01/myocarditis-covid19.php
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