Misleading: The article emphasized the risks of vaccine-associated myocarditis without clarifying that COVID-19 itself entails a greater risk and severity of myocarditis and other cardiovascular complications, providing readers with a distorted vision of the reality.
FULL CLAIM: “Myocarditis and pericarditis only occur after vaccination and not after COVID-19 infection.”; “Myocarditis and pericarditis were only documented in the vaccinated.”
REVIEW
Initial clinical trials demonstrated that COVID-19 vaccines are safe and effective against severe disease[1,2], leading to their authorization and approval by health authorities in many countries. Post-marketing surveillance confirmed that the benefits of COVID-19 vaccines outweigh their risks, but also revealed side effects that couldn’t be detected in trials due to their rarity. One such side effect now associated with the mRNA vaccines is a higher risk of myocarditis.
Myocarditis—as well as pericarditis—are conditions that arise due to heart inflammation. They can have various causes, but the most common is viral infection. Symptoms include chest pain, tachycardia (abnormally rapid heartbeat), and shortness of breath.
Vaccine-associated myocarditis usually arises in the days following COVID-19 vaccination and mostly affects young men. However, this side effect is rare; its incidence has been estimated at between 0.08 to 3 cases per 100,000 vaccinated individuals[3-6]. Vaccine-associated myocarditis is usually mild, with a rapid recovery[7].
In June 2024, the news outlet The Epoch Times claimed that new data from England’s National Health Service (NHS) showed that “myocarditis and pericarditis only occur after vaccination and not after COVID-19 infection.” The Epoch Times has repeatedly published vaccine misinformation.
Opponents of vaccination have often used the fact that myocarditis is a rare but proven side effect of vaccination to spread misinformation about COVID-19 vaccine safety. This is typically done by exaggerating the risks of myocarditis or failing to put them in perspective with the risks posed by COVID-19 itself, as Science Feedback explained on several occasions.
The June 2024 claim from The Epoch Times is no different. According to the outlet, a May 2024 preprint (a study that hasn’t yet been peer-reviewed) by Andrews and colleagues assessing COVID-19 vaccine effectiveness among children and teenagers[8] found that “myocarditis and pericarditis were only documented in the vaccinated”. However, The Epoch Times misrepresented the work by Andrew et al. and failed to put the risk of myocarditis after vaccination in perspective with the risk of cardiovascular complications caused by COVID-19 itself. We provide details below.
What the study did
Andrews et al. gathered data on the vaccination status of over 400,000 teenagers and 150,000 children in England. They assessed the effectiveness of the COVID-19 vaccines by comparing the risks of SARS-CoV-2 infection, COVID-19-related hospital visits, admissions to critical care units (ICUs), and COVID-19 deaths among individuals who received two doses of vaccine, one dose of vaccine, and those who were unvaccinated.
The authors also evaluated the vaccines’ safety by comparing the incidence of non-COVID hospital visits and myocarditis among these groups. In the vaccinated group, more than 25,000 people were diagnosed with COVID-19 and twelve people developed heart inflammation.
Andrews et al. found that teenagers receiving one dose of vaccine had a lower risk of getting COVID-19 in the two weeks following vaccination and a lower risk of COVID-related visits to the hospital compared to those who were unvaccinated. There were no COVID-related admissions to ICU or deaths, so no statistical conclusions could be drawn for these outcomes. The rarity of COVID-related outcomes in children under 12 prevented researchers from drawing meaningful conclusions about the vaccine’s effectiveness in this group.
Andrews et al. didn’t compare the risk of myocarditis after vaccination and COVID-19
In order to support The Epoch Times’ claim that myocarditis “only occur[s] after vaccination and not after COVID-19 infection”, one would need to compare people who were exposed to one of two things: a COVID-19 vaccine or COVID-19, but not both. If a vaccinated person also got COVID-19 and then developed myocarditis, it would be impossible to know for sure if the cause was the vaccine or COVID-19 without additional information.
More specifically, the clinical study would need to compare the occurrence of myocarditis in two groups: unvaccinated individuals who got COVID-19 during the duration of the study, and vaccinated individuals who didn’t get COVID-19 during the follow-up.
However, Andrews et al. didn’t make such a comparison. As explained earlier, they compared vaccinated and unvaccinated people. But we don’t know whether some of the individuals with heart inflammation also had COVID-19, which could also have caused the inflammation. Thus, the study didn’t provide the necessary information to support The Epoch Times’ claim. We reached out to the corresponding author of the study and will update this review if new information becomes available.
Risks of cardiovascular complications are higher after COVID-19 than after vaccination
Reporting on the vaccine-associated risk of myocarditis is nothing new. Health authorities, such as the U.S. Centers for Disease Control and Prevention (CDC) or the European Medicines Agency (EMA), already acknowledged the risks. The U.S. Food and Drug Administration (FDA) updated the vaccines’ fact sheets accordingly in 2021.
However, it’s important to keep in mind that vaccine-associated myocarditis is usually mild and the risk of heart inflammation is actually higher following COVID-19 than vaccination. Pediatric cardiologists Frank Han and Jennifer Huang wrote in a piece published by The Conversation, that not only was “the overall myocarditis risk significantly higher after an actual COVID-19 infection compared with vaccination”, but “the prognosis following myocarditis due to the vaccine [was] better than from infection”.
Supporting that statement, a meta-analysis of studies investigating the risk of myocarditis found that this risk was seven times higher after COVID-19 than following vaccination[9] among adults. Similarly, an analysis of U.S. medical records showed that the risk of heart inflammation was 1.8 to 5.6 times higher following COVID-19 than following vaccination[10] among boys aged 12-17.
Furthermore, focusing solely on the relative risks of myocarditis is misleading. While vaccination may cause mild cases of myocarditis in some rare cases, COVID-19 is associated with other, more severe cardiovascular complications, such as blood clots and heart attacks. An analysis of England’s health records showed that the risk of such cardiovascular complications was higher in people with COVID-19 and that vaccination reduced that risk[11].
A clinical consensus document from the Heart Failure Association of the European Society of Cardiology[6] summarized these observations as follows:
“The majority [of myocarditis] are mild and not associated with hospitalization or severe complications. This risk has to be balanced against the much greater risk of death, pulmonary, vascular, and cardiac complications by the SARS‐CoV‐2 virus itself.”
And:
“In all age groups studied, the overall risks of SARS‐CoV‐2 infection‐related hospitalization and death are hugely greater than the risks from post‐vaccine myocarditis.”
In summary, the analysis of NHS data by Andrews et al. illustrated that COVID-19 vaccines reduced the risk of severe COVID-19 in teenagers. Although some of the vaccinated teenagers developed myocarditis, the study wasn’t designed in a way that allowed them to determine whether the cause of heart inflammation was COVID-19 or vaccination.
The clinical data available so far shows that COVID-19 is more dangerous to the cardiovascular system than vaccination, as the disease is more likely to cause severe cases of myocarditis, in addition to other complications such as blood clots and stroke. But the risk of these cardiovascular complications from COVID-19 is reduced by vaccination. On balance, the benefits of COVID-19 vaccination outweigh their risks.
REFERENCES
- 1 – Baden et al. (2020) Efficacy and Safety of the mRNA-1273 SARS-CoV-2 Vaccine. The New England Journal of Medicine.
- 2 – Polack et al. (2020) Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine. The New England Journal of Medicine.
- 3 – Wong et al. (2022) Risk of myocarditis and pericarditis after the COVID-19 mRNA vaccination in the USA: a cohort study in claims databases. The Lancet.
- 4 – Oster et al. (2022) Myocarditis Cases Reported After mRNA-Based COVID-19 Vaccination in the US From December 2020 to August 2021. JAMA.
- 5 – McDonald et al. (2024) Myocarditis and Pericarditis Following mRNA COVID-19 Vaccination: 2024 Status and Management Update. Canadian Journal of Cardiology.
- 6 – Heidecker et al. (2022) Myocarditis following COVID‐19 vaccine: incidence, presentation, diagnosis, pathophysiology, therapy, and outcomes put into perspective. A clinical consensus document supported by the Heart Failure Association of the European Society of Cardiology (ESC) and the ESC Working Group on Myocardial and Pericardial Diseases. European Journal of Heart Failure.
- 7 – Heymans & Cooper (2021) Myocarditis after COVID-19 mRNA vaccination: clinical observations and potential mechanisms. Nature Reviews Cardiology.
- 8 – Andrews et al. (2024) OpenSAFELY: Effectiveness of COVID-19 vaccination in children and adolescents. MedRxiv.
- 9 – Voleti et al. (2022) Myocarditis in SARS-CoV-2 infection vs. COVID-19 vaccination: A systematic review and meta-analysis. Frontiers in Cardiovascular Medicine.
- 10 – Block et al. (2022) Cardiac Complications After SARS-CoV-2 Infection and mRNA COVID-19 Vaccination — PCORnet, United States, January 2021–January 2022. Morbidity and Mortality Weekly Report.
- 11 – Cezard et al. (2024) Impact of vaccination on the association of COVID-19 with cardiovascular diseases: An OpenSAFELY cohort study. Nature Communications.
