Thread by @michaelzlin

What the early omicron data means: get boosted.

"BNT162b2+infection" are people infected in 1st wave, then Pfizer-vaxxed (2 shots). They have better neutralization of omicron than only Pfizer-vaxxed .

A RNA boost 6mo after your last shot bumps Ab levels by 10x. You may need it.

https://twitter.com/_b_meyer/status/1468319835012673549

Some details: The 100x higher antibody levels of the infected+Pfizer vs Pfizer here is somewhat artifactual. The vax-only are ony 12 days post-vax. That's well before peak antibody response at 3-8 wks post-vax. OTOH the infection+vax are 27 days post-vax, so near peak protection.

Previous studies saw only a 2–10x difference in Ab levels between infection+vax and vax. So the 100x difference here is likely from the vax-only being sampled before their response is mature.
thelancet.com/journals/lanmi…

Anyway, omicron requires 40x higher antibody levels for neutralization compared to original strain (today's result). By comparison, Delta required 4x more.

Boosting is able to give you 2x more antibodies than needed to protect 90% against Delta disease. As omicron requires 10x higher titres to get the same protection as Delta, that means it won't be possible for current vax+boost to provide 90% protection against omicron.

Still, the more Abs the better the protection vs omicron. Boosters also likely bring in additional naive B and T cells to serve as memory cells for an omicron challenge. So boosters, so long derided in the media as not necessary, turn out to be very useful indeed.

Here's a nice study comparing 2xPfizer ("fully vaccinated") to 3xPfizer ("boosted") to infection+2xPfizer. In panel A are nAb titers. Gray is vs Delta, red Omicron.

3xPfizer as good as infection+2xPfizer.

No need to travel back in time to get infected before your vaccine now.