Check out this Kaiser Permanente Northwest study which points out the flaw in the "first 1-7 days" logic:

https://onlinelibrary.wiley.com/doi/10.1002/pds.5439

> The encounter methodology identified 14 distinct patients who met the confirmed or probable CDC case definition for acute myocarditis or pericarditis with an onset within 21 days of receipt of COVID-19 vaccination. When we extended the search for relevant diagnoses to 30 days since vaccination, we identified two additional patients (for a total of 16 patients) who met the case definition for acute myocarditis or pericarditis, but those patients had been misdiagnosed at the time of their original presentation. Three of these patients had an ICD-10-CM code of I51.4 “Myocarditis, Unspecified;” that code was omitted by the VSD algorithm (in the late fall of 2021). The VSD methodology identified 11 patients who met the CDC case definition for acute myocarditis or pericarditis. Seven (64%) of the 11 patients had initial care for myopericarditis outside of a KPNW facility and their diagnosis could not be ascertained by the VSD methodology until claims were submitted (median delay of 33 days; range of 12–195 days). Among those who received a second dose of vaccine (n = 146 785), we estimated a risk as 95.4 cases of myopericarditis per million second doses administered (95% CI, 52.1–160.0).

One of the author also did a podcast where she pointed out how the way some insurance claims (especially those from outside facility) works is that it takes a few weeks to receive the claim and it to get registered correctly. So they often get missed in short period windows.

When they took into account the correct numbers, they found rates of 537.1 per million for MALES aged 18-24.

Here in Ontario, our government reports rates of 200.2 per million in males aged 18-24. Note that Ontario stopped giving Moderna to under 30 year olds and also made the dosing interval to be 8 weeks but our rates of myocarditis continued to climb.

> most people don’t suffer chronic forms

This is misleading. There is no such thing as mild myocarditis. Inflammation of your heart muscle has to be taken seriously, even if you end up in the hospital for a couple days, that's not the end of inflammation because it leads to scarring and permanent damage. Heart is the only organ that's going to keep you alive the longest and any damage to the heart has to be taken seriously especially if you are balancing it with a condition that in itself is very low risk to youth.

Around 88% of the cases occur in males and up to 96% of the cases are hospitalized. Requires no exercise for 6 months and 6 month follow up Cardiac MRI still shows damage:

https://www.jpeds.com/article/S0022-3476(22)00282-7/fulltext

And since the COVID vaccine doesn't prevent infection, you may end up compounding the risk if you get myocarditis first from the vaccine and then again from infection.

The largest study on this topic has been of 23.1 million residents across four Scandinavian countries — Denmark, Finland, Norway, and Sweden. They found that:

> in young men 16 to 24 years of age, the risk for myocarditis after vaccination with either the Pfizer or Moderna vaccine is higher than the risk for myocarditis after COVID-19 infection.

> "We show that the risk of myocarditis after COVID infection is lower in younger people and higher in older people, but the opposite is true after COVID vaccination, where the risk of myocarditis is higher in younger people and lower in older people"

> "In the group at highest risk of myocarditis after COVID vaccination — young men aged 16 to 24 — the Pfizer vaccine shows a five times higher risk of myocarditis versus the unvaccinated cohort, while the Moderna vaccine shows a 15 times higher risk"

https://www.medscape.com/viewarticle/972453

Actual study:

https://jamanetwork.com/journals/jamacardiology/fullarticle/...

This finding from Scandinavian countries also seems to match the update to the Nature study which found the risk of myocarditis in under-40 males to be greater from the vaccine than from COVID. Discussed here few months ago:

https://news.ycombinator.com/item?id=29697780