Instagram post's claims about myocarditis in children not supported by official data

An Instagram post with over 20,000 likes features a screenshot of a tweet claiming:

Prior to the ‘pandemic’, myocarditis in children was 4 cases per million.

Current estimates are 25,000 cases per million.

This is genocide.

This 25,000 per million figure, which has also been used by others, appears to be far too high.

The post in question does not provide a source, but it may come from Dr Peter McCullough, a doctor in the US who has made these claims before based on limited evidence, referring to people recently vaccinated against Covid-19 specifically.

Official figures from the Joint Committee on Vaccination and Immunisation (JCVI) and the Medicines and Healthcare products Regulatory Agency (MHRA) estimate the risk of myocarditis in children following Covid vaccines to be at most around 35 cases per million.

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, including specifically about myocarditis risk, and on claims made by Dr McCullough.

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.

Although the Instagram post itself appears only to be talking about the “current” general rate of myocarditis in children, it may be misquoting figures used elsewhere to talk about the risk of myocarditis following a Covid-19 vaccination specifically.

This may occur very rarely with 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. 

Where do these figures come from?

The claim that there were “4 cases per million” in children before the pandemic seems to come from Dr McCullough, who says it comes from a Finnish study—although we can’t find anything in the study that suggests this. We have contacted Dr McCullough to ask for clarification on the claims.

The study says: “The incidence rate in children aged 0 to 15 years was 1.95/100 000 person-years.” This would amount to 19.5 cases per million each year, not four—and it describes hospital admissions with myocarditis, not the underlying rate at which it occurs, which may be much higher. The study itself says the condition is “probably underdiagnosed because it may be asymptomatic in a considerable number of patients”.

In short, the study is not designed to tell us the true rate of myocarditis in children, and it does not do so, but it does suggest that it is much higher than four cases per million each year.

What about the 25,000?

The claim that there are currently “25,000 cases per million” also seems to come from Dr McCullough, who says that two different studies suggest it. 

One of the papers is about “myocardial injury” in Swiss adults after vaccination—not myocarditis in children. However, the study does not give any evidence to substantiate its claim that the vaccine caused the cases it detected. Nor did it report any analysis which would demonstrate whether the results it found were significant. It is written in French, and we have relied on automatic translating.

The paper showed a 2.8% rate of myocardial injury that it attributed to vaccination because, in its words, “no other cause than the vaccine was implicated”. This percentage would equate to a rate of 28,000 per million.

The second paper did look at children. It analysed data on 301 13-18 year-olds, two thirds of them male, after their second mRNA Covid vaccine dose. It reported “one case of myopericarditis [inflammation of the heart’s outer sac as well as the muscular wall], four cases of subclinical myocarditis, and two cases of pericarditis” among them. These make up 2.3% of the sample—this would be 23,000 in a million if equated out.

The study did not include a control group, so it can’t tell us whether the children who had the vaccine were more likely to have these conditions than their peers.The study also can’t tell us that the vaccine caused these cases, all of which were “mild and transient”.

Full Fact approached the authors of these papers, and Dr McCullough, for comment.

Is more reliable data available?

The JCVI, which advises the UK government on vaccine strategy and evidence, has estimated that the risk of myocarditis for children aged 12-15 following vaccination is about 3-17 cases per million first doses and 12-34 cases per million second doses.

A systematic review published in the BMJ looking at data up to January 2022 estimated a rate of less than 20 cases per million for children aged 5-11 years after a second dose of the Pfizer vaccine. For boys specifically aged 12-17 this might be between 50 and 139 cases per million, with girls more likely to again be under 20 per million. These are low-certainty estimates, largely because the events are so rare.

The MHRA, which regulates vaccines in the UK, says: “In those aged under 18 years, the reported rate for heart inflammation (myocarditis and pericarditis) was 13 per million first doses and 8 per million second doses of the monovalent Pfizer/BioNTech vaccine; these are lower than the reporting rates seen in young adults.”

Image courtesy of Alaa Najjar