Thread by @davidwdowdy

A visual representation of what we know and don't know about waning immunity.

We know, at 6-8 months:
- Partial vax not great.
- Full vax ~70-85% effective (better vs severe disease than infection).
- Booster gives short-term bump.

We don't know what happens next.
4 scenarios:

Scenario A: Booster gives long-term benefit (by increasing immune memory), and immunity to 2-dose series continues to wane.

In this scenario, boosters are the right thing to do, now.

Scenario B: Booster doesn't improve immune memory, so the added effect of booster is short-lived.

This is the worst-case, and in my mind least likely - because vax has been effective, w/o booster, for 8 months now.

Here, booster helps a bit, but we need revised vax.

Scenario C: Booster improves memory response, but current vax continues to work well.

Booster here is helpful, but not immediately urgent. Since current vax remains effective, we have time to wait for more data.

I'm an optimist at heart, like to think this is most likely.

Scenario D: Two-shot series works well long-term, booster doesn't add much.

In this case, the effect of the booster is small and short-lived.

Meaning boosters aren't that useful, and if used, the best time to give booster is at the start of a surge.

Best policy?

A: Booster now
B: Prioritize revised vax
C: Booster non-urgently
D: No universal booster

In all cases, vax immunocompromised. And if someone wants booster, likely doesn't hurt.

But we don't know which (A-D) is true.

My take: far-reaching policy w/o data is risky.