Myocarditis (inflammation of the heart muscle) and Pericarditis (inflammation of the tissue around the heart) is the most serious known side-effect of the Moderna and Pfizer/BioNTech mRNA vaccines. The risk is primarily found in male adolescents approximately age 12-21.
"The risk of vaccine-associated myocarditis is small, with up to an additional 2 events per million people in the 28-day period after exposure to all vaccine doses other than mRNA-1273. This is substantially lower than the 35 additional myocarditis events observed with SARS-CoV-2 infection before vaccination." https://www.ahajournals.org/doi/full/10.1161/CIRCULATIONAHA.122.059970 (2022-08-22)
This CDC study uses data from 40 healthcare systems to estimate the risk of myocarditis by gender and age. The tables provide the incidence rate per 100,000 persons for myocarditis following vaccination or infection.
"Two studies from Israel quantify the risk of myocarditis following the Pfizer–BioNTech shot, with one suggesting the chance of developing the condition is about one in 50,000."
A study involving 6,158,584 men under 40 (the highest risk group), excess myocarditis events is estimated at 11 events per million following a second dose of Pfizer and 97 events per million following a second dose of Moderna, and 11 events per million following a second dose of AstraZeneca. Myocarditis risk was significantly less for first dose and booster doses. See table 4.
Data from 40 healthcare systems involving millions of individuals showed that teen boys age 12-17 have 2-6 times higher risk of heart complications after infection compared to after vaccination (Moderna or Pfizer) and young men age 18-29 had 7-8 times higher risk.
"Most cases of suspected COVID-19 vaccine myocarditis occurring in persons <21 years have a mild clinical course with rapid resolution of symptoms." (American Heart Association Journal)
"Whilst myocarditis can be life-threatening, most vaccine-associated myocarditis events have been mild and self-limiting. The risk observed here is small and confined to the 7-day period following vaccination, whereas the lifetime risk of morbidity and mortality following SARS-CoV-2 infection is substantial."
"We report 7 cases of acute myocarditis or myopericarditis in healthy male adolescents who presented with chest pain all within 4 days after the second dose of Pfizer-BioNTech COVID-19 vaccination... All 7 patients resolved their symptoms rapidly." (American Academy of Pediatrics)
"As of June 2021, the Vaccine Adverse Event Reporting System (VAERS) reported 1,226 cases of myocarditis after COVID-19 vaccination... Among a subset of 323 patients determined to have myocarditis after the vaccines, the vast majority were male (90%) with mild clinical cases and none had died." (Myocarditis Foundation)
"In the overall population... the risk of hospitalization or death from myocarditis was higher after SARS-CoV-2 infection than vaccination and was greater after the first 2 doses of mRNA vaccine than after adenovirus vaccine"
For more detail, see Table 4 in the above paper, which estimates excess myocarditis events per million following infections with and without vaccination in a variety of demographics.
In a study involving nearly 43 million people, only young males receiving a second dose of Moderna MRNA-1273 had similar risk of myocarditis compared to infection. "the risk of myocarditis is substantially higher after SARS-CoV-2 infection in unvaccinated individuals than the increase in risk observed after a first dose of ChAdOx1nCoV-19 vaccine, and a first, second, or booster dose of BNT162b2 [Pfizer] vaccine." https://www.ahajournals.org/doi/full/10.1161/CIRCULATIONAHA.122.059970 (2022-08-22)
"although the risk of myocarditis with SARS-CoV-2 infection remains after vaccination, it was substantially reduced, suggesting vaccination provides some protection from the cardiovascular consequences of SARS-CoV-2" https://www.ahajournals.org/doi/full/10.1161/CIRCULATIONAHA.122.059970 (2022-08-22)
"vaccine-associated myocarditis was largely restricted to men younger than 40 years with 1 exception; both younger men and women were at increased risk of myocarditis after a second dose of mRNA-1273" https://www.ahajournals.org/doi/full/10.1161/CIRCULATIONAHA.122.059970 (2022-08-22)
"we found that the risk of myocarditis is more than seven fold higher in persons who were infected with the SARS-CoV-2 than in those who received the vaccine. These findings support the continued use of mRNA COVID-19 vaccines among all eligible persons per CDC and WHO recommendations."
Meta-analysis based on 22 studies: https://www.frontiersin.org/articles/10.3389/fcvm.2022.951314/full (2022-08-29)
"In the largest study of its kind to date researchers have found that 1 in 8 people hospitalised with COVID-19 subsequently developed myocarditis, with the severity of infection most closely linked to the severity of long-COVID symptoms."
"We estimated extra myocarditis events to be between 1 and 10 per million persons in the month following vaccination, which was substantially lower than the 40 extra events per million persons observed following SARS-CoV-2 infection."
Study found that Pfizer/BioNTech vaccine increased myocarditis risk by 1 event per million patients and Moderna increased myocarditis risk by 6 events per million patients, but a positive COVID-19 case increased myocarditis risk by 40 events per million patients, 6 to 40 times higher than the mRNA vaccines.
"While the overall incidence of myocarditis following COVID-19 infection is low, persons with COVID-19 have a nearly 16-fold increase in risk for myocarditis, compared to individuals without COVID- 19"
A study involving 6,158,584 men under 40 (the highest risk group for vaccine myocarditis), excess myocarditis events is estimated at 11 events per million following a second dose of Pfizer, and 16 events per million infections without vaccination. No excess myocarditis events are detected following infection in this group when vaccinated. See table 4.
"Emerging Canadian safety surveillance data suggest an extended interval between the first and second dose may reduce the risk of myocarditis/pericarditis associated with the second dose of an mRNA COVID-19 vaccine (note this data is currently under preparation for publication)"
The European Medicines Agency (EMA)'s Pharmacovigilance Risk Assessment Committee indicated they had started looking into cases of Myocarditis in May 2021
A month later, the committee provided an update. A causal link had not yet been established, however Myocarditis is known to be associated with infections and vaccines. "Most of these cases were mild and resolved within a few days."
A month later, on July 9, EMA concluded that cases of myocarditis and pericarditis could be causally associated with vaccination and recommended listing them as side effects. By this time 5 cases had ended in death, and all "were either of advanced age or had concomitant diseases". Healthcare providers were advised to monitor for the condition. "Healthcare professionals should be alert to the signs and symptoms of myocarditis and pericarditis. They should tell people receiving these vaccines to seek immediate medical attention if symptoms indicative of myocarditis or pericarditis occur."
From the Mayo Clinic "Usually, myocarditis goes away without permanent complications." https://www.mayoclinic.org/diseases-conditions/myocarditis/symptoms-causes/syc-20352539 (accessed 2021-12-27)
False. Myocarditis was linked to Covid-19 very early in the pandemic. This review "COVID-19 and Myocarditis: What Do We Know So Far?" was published in July 2020: https://www.sciencedirect.com/science/article/pii/S2589790X20300640
The reason you heard about it more after it was linked to vaccination is that anti-vaccine advocates are highly motivated and very effective at amplifying stories that fit their narratives.
This study can be found here: https://www.mdpi.com/2077-0383/11/8/2219
It includes the following text which has been spread by conspiracists:
"Post COVID-19 infection was not associated with either myocarditis (aHR 1.08; 95% CI 0.45 to 2.56) or pericarditis (aHR 0.53; 95% CI 0.25 to 1.13). We did not observe an increased incidence of neither pericarditis nor myocarditis in adult patients recovering from COVID-19 infection."
This study looked at "Post COVID-19 Unvaccinated Patients" (it's in the title), NOT people who have recovered from myocarditis or pericarditis. It only included patients who have completely recovered from COVID:
"The post-COVID timeframe was defined from at least ten days after the date of positive PCR test contingent upon lack of symptoms related to COVID-19 infection, according to the definitions of the Israeli Ministry of Health."
The study did not look at people who are currently infected and did not draw any conclusions about whether myocarditis is associated with active infection.
Is the study correct that Post COVID-19 infection is not associated with myocarditis? Other studies disagree.
Here is a much larger (over 1 million people) and longer (12 months) study that is published in a much more rigorous journal - Nature.
Title: "Long-term cardiovascular outcomes of COVID-19"
"We show that, beyond the first 30 d after infection, individuals with COVID-19 are at increased risk of incident cardiovascular disease spanning several categories, including cerebrovascular disorders, dysrhythmias, ischemic and non-ischemic heart disease, pericarditis, myocarditis, heart failure and thromboembolic disease."
"Our results provide evidence that the risk and 1-year burden of cardiovascular disease in survivors of acute COVID-19 are substantial."
Another problem with the Israel study is that it only looked at a small number of myocarditis/pericarditis ICD-10 codes. Excluded Viral myocarditis (B33.22 and B33.23), for example.
This topic is discussed in greater detail by Dr. Susan Oliver, who points out many limitations of the Israel study, and responds to criticism of the US study in this video: https://www.youtube.com/watch?v=rASCfU6OXVk&t=1s
The study: https://www.mdpi.com/2414-6366/7/8/196 (2022-08-19)
Preprint: https://www.preprints.org/manuscript/202208.0151/v1 (2022-08-08)
This study involved 301 participants age 13-18 receiving their second dose of the Pfizer vaccine.
One participant was diagnosed with myocarditis. This patient's symptoms resolved within days with no detectable damange. A followup MRI at 5 months showed complete recovery and no scar.
"Chest pain is an alarming symptom in patients receiving BNT162b2 mRNA COVID-19 vaccination, especially a second dose of BNT162b2. The risk for these symptoms was found to be higher than reported elsewhere. The adverse cardiovascular manifestations observed in this adolescent cohort were both mild and transient."
Fact Check-Study of Thai teenagers did not find one third experienced heart effects after COVID vaccination
False. more info...