No cross-strain protective immunity? Based on what evidence? Even the linked story—which @UW_IHME wrote—says nothing of the kind.

I think people still listen to @UW_IHME even after last spring's modeling fiasco. If so, this is dreadfully irresponsible. If not, it's still false. https://twitter.com/IHME_UW/status/1356639890952216578

The Johnson & Johnson trial reported substantial cross protection against symptoms and against severe disease for the B.1.351/501Y.V2 variant that is causing so much concern.

There is *no known strain* for which there is "no cross-strain protective immunity".

Looks like this is a direct quote from Chris Murray. He's basing this on the Novavax placebo arm, in which that seropositve and seronegative people were equally likely to develop disease. But the study was not designed to test this and wasn't randomized. https://twitter.com/IHME_UW/status/1357048958158180352

To elaborate a little, one issue is that seropositive people who already had the virus likely have different exposure risk than seronegative people who didn't already have the virus. You can't just compare them apples-to-apples.

Anyone remember who wrote a nice thread on this?