Thread by @buzzhollandermd

I appreciated the kind words of Prof Morris:
And, more reluctantly, the observation of one of his numerically-literate followers that I’d mis-characterized a CDC study on odds of getting myocarditis from Covid-19.
The “you’re 16X more likely to get myocarditis from covid” study.

https://twitter.com/jsm2334/status/1453217817738809350

I have seen that figure referenced twice in the last 24 hr, despite the study being 2 mo old.
It’s relevant now, in that lots of people are trying to assess the risk of myocarditis in kids if they choose/are mandated to have the vaccine vs if they do not.
My mistake?

I missed that this “hospital-based” study included hospital-based OUTPATIENT clinics where people were diagnosed with covid:
cdc.gov/mmwr/volumes/7…
I had assumed that the denominator was all hospitalized patients, when really it was an unstated mix of inpatients and outpatients.

In retrospect, not I nor anyone should reference this study like it is useful for making population estimates.
Since hospitalized ppl are different than un-hospitalized ppl, it’s best to either use a whole population watershed (like the Israeli study on covid v vaccine events);

Or just limit a study to hospitalized patients, as this is an accepted study design (albeit one with limited extension to the general population).
This MMWR did neither, mixing the two groups in an unstated proportion.

We’re left with the question, “16X more likely to get myocarditis than… whom?”
If the incidence rate of myocarditis from covid is very low, then being 16X higher does not imply the risk is greater from virus than vaccine - since mandates would require the vaccine for everyone.

We get from CDC’s COVID-NET population-based data that total hospitalizations for age 5-17 with covid is about 1/1500-2000 per annum. Unless a third of those kids are being diagnosed w/ myocarditis (and the MMWR suggests it’s <1%), the vaccine-induced risk is higher.
Far higher.

I hate pushing my mistakes out into the world.
But I’m grateful for when they are pointed out.
I’ll write the study author to see if they have the data on the mix of hospitalized covid cases vs outpatient.
Meanwhile, I wouldn’t this study as a justification for vaccine mandates.