Thread by @buzzhollandermd

The reaction to the recent CDC MMWR on immunity after covid infection being 5X less protective than vaccination shows off everything that has been wrong about science communication through this pandemic.
cdc.gov/mmwr/volumes/7…
“Told ya so” -
Seriously?

Public Health voices got their Gotchas in for anyone in anti-vax, anti-mandate, or just anti-establishment camps who ever dared to argue that we should consider immunity from prior infection on par with vaccination in terms of protection from disease.
But what DID the study show?

A: Not much.
Anyone claiming this study shows that unvaccinated people with prior infection are 5X more likely to be hospitalized than fully vaccinated people, probably either did not read the study, or did not understand it.
And should not be tweeting about it.

Put briefly, to do a study like this, you’d want a lg watershed of people for whom you have solid data on infection/vaccination history w/in a time frame (our denominators), and then complete data on that same watershed on who got sick later w/ covid (our numerators).
Like this:

That was our earlier Israeli pre-print:
medrxiv.org/content/10.110…
It checked all the boxes: large HMO, reliable records, sound study design.
It found prior infection far more protective vs symptomatic infection (7X) and also more protective vs hospitalization.
So what gives?

What did this CDC MMWR measure?
Numerator was covid hospitalizations;
Denominator was… people w/ vaccination w/in 6 mo vs people w/ prior infection who were hospitalized for respiratory infections. Not the whole watershed. Just those inpatients. 90+% of whom DID NOT HAVE COVID.

Hmmm. If about 50-60% of ppl are fully vaccinated in those areas; and maybe 15-20% of ppl are unvaxed but had prior infection; you might conclude: ppl w/ prior infection got really sick less than vaccinated ppl. And had less severe covid, too.
But you would just be guessing.

One thing that is conclusive, though, is that the study’s headline is not true.
You cannot possibly infer that vaccinations out-protected prior infection from this study.
Amazingly these limitations did not make it into the authors’ *discussion* of study limitations. 🤔

And apparently didn’t make into the heads of those who proclaimed these results as if they were decisive.
We wonder why the vax-hesitant don’t trust public health voices?
We’ve got to start by being honest.
I’m still quite happy my first covid exposure will come after a vaccine.