In COVID-19, not all myocarditis is the same

welcome Impact FactorEach week we bring you commentary on new medical research. I'm Dr. F. Perry Wilson from the Yale School of Medicine.

After George Washington Use of live smallpox to vaccinate Revolutionary War soldiers 1777. The COVID vaccine may be the most controversial in U.S. history. Should That may be debatable. I'm one of those who look at the data and take the side of reasonable efficacy and minimal safety risks. But we can't deny the reality here. The public is Skepticism about COVID vaccines grows than influenza For example, vaccines, RSV vaccines, etc. This is true for Republicans and Democrats alike, although the latter group is generally less hesitant about getting vaccinated.

There are many reasons for skepticism about COVID vaccines that are, in my opinion, unjustified: vague messaging about efficacy, poor communication about the underlying mRNA technology, and of course, Myocarditis thing.

A small number of people have been found to develop myocarditis (inflammation of the heart muscle) after receiving the Pfizer or Moderna mRNA-based COVID vaccines. Complicating the risk-benefit calculation, the people who appear to be at highest risk of vaccine-associated myocarditis are also those at lowest risk of dying from COVID: young men.

So how does a young man decide whether it's worth getting the vaccine? Most public health officials position this as a balance between the risk of myocarditis (low) and the risk of COVID complications (also low). But what seems to be overlooked is that myocarditis can also result from COVID infection.

You know, folks, we're talking about a very small percentage here. Most of the data is

First, recall that myocarditis can occur within 7 days after vaccination. Rates range from as low as 1 in 3 million in older adults to as high as 1 in 10,000 in 16- to 17-year-old males..

As I said earlier, myocarditis can also occur after COVID infection. This study They found that in men under 40, there were 16 excess cases of myocarditis per million after infection, compared with 97 after the second dose of the Moderna vaccine. However, in the population as a whole, there were more cases of myocarditis due to infection than due to the vaccine.

Nevertheless, these million People are getting myocarditis. Myocarditis is not the only thing COVID-19 causes. It can be fatal. But it does make the decision a little bit more complicated, especially for young, healthy men.

There's one more important piece of information we needed to know, and we're happy to say the answer is finally revealed. The study was published this week JAMA. Is post-vaccination myocarditis worse, better, or the same as post-COVID-19 myocarditis?

To answer this question, the researchers took advantage of France's national health system, which has almost complete data on the entire population of the country. Epidemiologically, I'm very envious of these European countries that have national health systems, but America has Waffle House.

The authors identified all patients aged 12 to 49 years who were hospitalized with myocarditis in France between December 2020 and June 2022. In a country of 68 million people, the total number was 4,635. It is important to remember that myocarditis is a very rare disease.

If myocarditis was diagnosed within 7 days of COVID vaccination, it was classified as post-vaccination myocarditis. If it was diagnosed within 30 days of COVID infection, it was classified as post-COVID myocarditis. And if it was neither, it was classified as traditional myocarditis, which accounts for the majority of all cases. We note that seven people were diagnosed with myocarditis within 7 days of COVID vaccination. and People who died within 30 days of COVID infection were excluded from the analysis.

So here we have three groups, and as you'd expect, they're quite different in terms of their baseline characteristics: Those who developed post-vaccination myocarditis were younger, more likely to be male, had less cardiac disease, respiratory disease, diabetes, and were generally healthier.

The main question the researchers had was: Is all myocarditis essentially the same? To find out, they looked at the outcomes that occurred after the initial hospitalization for myocarditis: readmissions for myocarditis, cardiovascular events, and heart failureThis explains the fact that people who have developed myocarditis after vaccination, including deaths, were originally healthy.

Here we show the hazard ratio, which is the relative proportion of a particular event between people with vaccine- or viral-induced myocarditis and those with traditional myocarditis, which form the reference group.

The pattern is pretty clear: post-vaccination myocarditis has a better outcome than classic myocarditis, and post-infectious myocarditis has a similar outcome to classic myocarditis.

This is not to say that post-vaccination myocarditis is benign. There is an event here. One person died, likely due to complications from post-vaccination myocarditis. Of course, there were four deaths in the post-infection myocarditis group.

These results held up in several related sensitivity analyses, including one in which people who developed myocarditis within 30 days of vaccination were classified as having postvaccination myocarditis, instead of the traditional seven-day period.

So what is going on here? It's not entirely clear. Logically, since both the vaccine and the virus cause myocarditis, something common to both must be the cause. And the two things common to both are the mRNA code and the spike protein that results from it. Given that the myocarditis is worse after infection, as seen in this study, it lends credence to the hypothesis that the spike protein is causing an inflammatory response to the heart muscle cells, possibly through molecular mimicry. It's just that in the case of the vaccine, the dose of the spike protein is self-limiting. But the COVID virus itself has the whole package of proteins to produce more spike protein than is inoculated. That's how life finds a way.

But let's answer the fundamental question at the heart of all these studies: Are the risks of the vaccine worth the benefits? The answer is that myocarditis is not the answer. Whether post-vaccination or post-COVID, this outcome is too rare to significantly influence rational decision-making. It's like deciding whether to carry a flask of whiskey in your pocket based on its ability to stop bullets.

To make an informed decision about vaccination, and with vaccination season fast approaching, totalling Risk and totalling Benefits. Most data suggests that for most people, the benefits significantly outweigh the risks. If we were the average human being, we would probably choose to get vaccinated.

However, humans are subject to what are called cognitive biases. Fear risk biasWhen the outcome itself is particularly egregious, we think of the outcome as more likely than it actually is. This is where the myocarditis story gets us in trouble and affects vaccination rates. Myocarditis is a horrible thing. And like a shark attack, we act as if the outcome is more likely than it really is.

I'm not saying you shouldn't worry about vaccine side effects or the effects of COVID — at the end of the day, these decisions are personal — but just because they're personal doesn't mean they aren't rational.

F. Perry Wilson, MD, MSCE, is an associate professor of medicine and public health and director of the Clinical and Translational Research Accelerator at Yale University. His science communication articles can be found on Huffington Post, NPR, and here on Medscape. He tweeted: Perry WilsonAnd his book, How drugs work and when they don't, is now available.