Thank you for your question. The largest trial I found was done in India which reported approximately 2 cases of myocarditis per 10 million vaccine doses.

As noted above, this was much lower than cases from the virus itself.

Regards
Cliff

Jaiswal V, Mukherjee D, Peng Ang S, et al. COVID-19 vaccine-associated myocarditis: Analysis of the suspected cases reported to the EudraVigilance and a systematic review of the published literature. Int J Cardiol Heart Vasc. 2023;49:101280. Published 2023 Dec 3. doi:10.1016/j.ijcha.2023.101280

That’s a lot of papers to trawl through, if you’d like to look at the report Myocarditis is on page 199, there should be a live link in the article to take you to a PDF. They focus mostly on the causality, so does getting a vaccine raise the probability that you will get myocarditis? It was someing like 1-2 cases per million, so already very small increase in risk. The tricky element of your question is how do you rate severe? So I looked into the death rates for you. Accordinfg to this paper, https://link.springer.com/article/10.1007/s00392-022-02141-9 from 2022, if you are hospitalised with myocarditis, normally you have a roughly 2% chance of dying. COVID-19 infection raises your risk of dying to 13%. In contrast according to this study and some others https://onlinelibrary.wiley.com/doi/10.1002/jmv.29693 mortality from vaccine induced myocarditis was 0.44%. If you think about it, most people who developed myocarditis bad enough to see a doc after a vaccine were teen boys, so I think that already makes mortality less likely! It couyld be that a lot more people had it but didn’t notice anything bad enough to visit a doc so were never diagnosed. So my guess is that the severity of the condition is far lower from vaccines than from getting COVID19. 0.44% mortality from myocraditis triggered by a vaccine, vs 2.3% mortality normally, vs 13.6% mortality of myocarditis plus COVID19 inbfection.

Did any of the articles or this review discuss the relative severity?

Hi Barclay, the energy molecule is ATP, made by the mitochondria from glucose metabolites and Oxygen. Remember the formula Glucose + Oxygen —> ENERGY+ water + carbon dioxide?
In this scenario glucose donates its electrons to oxygen and in the process of breaking bonds energy is produced. That energy is stored in ATP a molecule that cells use to operate their proteins. So for regular ATP production the fuel is glucose metabolites.

When you run out of oxygen and/or glucose to power the ATP making process, your muscles use a different form of fuel to make ATP: phosphocreatine and glycogen.

These molecules are long term emergency stores that take a while to be processed and transported around the body. If your muscles find it difficult to use Oxygen to make muscles they are constantly tapping into their glycogen and phoshocreatine reserves. This makes it a much slower prorcess to refill the stores sitting in their cells for emergency.

It’s like if you start using a savings account to pay your bills- it takes a lot longer to replace those savings if you have to keep dipping in cos there’s no money in your current account.

Did this this help? Happy to answer any questions I can!