Myocarditis after Covid vaccines doesn’t kill one in five

A video on Facebook contains claims about the death rate from myocarditis after the Covid-19 vaccines. The claim is misleading and not backed up by the data.

Myocarditis is very rare after Covid vaccination, as we have written about before, and the rate after Covid infection itself is higher. False information about the Covid vaccines is common, and may lead to people making bad decisions about their health. We have written many times before on this issue, and specifically about myocarditis risk.

The video

The video has circulated on social media recently, with the oldest we could find being posted to YouTube over a year ago. It features audio apparently of a man talking to a pharmacist about his son, who he says has been admitted to hospital with myocarditis after receiving the Covid-19 vaccine. The audio contains a number of general claims about the vaccines and children.

The man says: “So you know what the prognosis is? You know what it is? Possible death within five years. 20% of people with myocarditis die. It is a permanent damaged heart.”

Claims about high death rates from myocarditis are common, with widely shared posts stating: “Myocarditis has a 20% fatality rate after 2 years and a 50% fatality rate after 5 years.”

A US healthcare education company StatPearls also gave a mortality rate of viral myocarditis of “up to 20% at 1 year and 50% at 5 years”, while acknowledging this varies depending on how severe the disease was at the time, among other factors. Full Fact contacted StatPearls for their source on this, and they told us the statement was incorrect and will be removed from the article.

What is myocarditis? 

Myocarditis is an inflammation of the muscular wall of the heart (the myocardium), most often caused by viral infection. Common symptoms include chest pain, fever and tiredness.

This may occur very rarely after the Pfizer and Moderna vaccines, although the risk of myocarditis following a Covid infection appears to be higher when looking at people of all ages. The benefits of vaccination for Covid-19 generally outweigh the risks for most people.

Official myocarditis incidence figures—the number of cases over a given time period, usually a year—are hard to come by, as many cases are mild and so not reported. 

This also complicates assessing the proportion of cases which are fatal (the mortality rate), as only more serious cases are known about. As a result this could lead to overestimates. Studies typically look at patients who have been admitted to hospital, which will be the more severe cases that cause enough symptoms that people seek help.

For example, a  2019 study of admissions to hospital in the NHS in England found a 4% all-cause mortality (death from any cause) for patients who were admitted to hospital with myocarditis between 1998 and 2017. 

It can cause permanent damage but the majority of cases do not lead to this, so it would be wrong to suggest that all cases of myocarditis lead to “a permanent damaged heart” as the video does.

A mild disease

The UK Health Security Agency says that: “myocarditis and pericarditis following vaccination is usually mild or stable and patients typically recover fully without medical treatment”, and that the long-term impacts aren’t yet known. 

The general rollout of the Covid vaccines in the UK was extended to children aged 12 and over in September 2021 and to younger children in April 2022, so it’s too early to have any reliable data on possible consequences of post-vaccine myocarditis. But early indications don’t support the video’s claim.

Dr Matt Oster, a paediatric cardiologist and medical officer at the US Centers for Disease Control and Prevention, told fact checkers at Reuters that “Myocarditis after COVID-19 vaccine has less occurrence of heart failure and has a milder acute clinical course” and that “short-term outcomes of myocarditis after COVID-19 vaccine are much better than those of typical viral myocarditis”, with long-term outcomes being researched.

The general Covid vaccination scheme has been wound down in the UK, but seasonal boosters are available to those at increased risk.

Featured image courtesy of Alaa Najjar