Thread by @alexandrosM

Why don't we have a delta-targeting vaccine available right now? I thought the promise of mrna tech was that it would be quick to adapt to variants?

I'll tell you the hypotheses I know of, you tell me yours.

Hypothesis 1. Regulation makes it difficult to push through a new variant vaccine.

Hypothesis 2. The iPhone effect: if people know a new vaccine is coming, they might hold off taking the existing one

Hypothesis 3. Original Antigenic Sin makes variant vaccines pointless.

Hypothesis 4. Delta evades vaccines mostly by higher viral load. There's not much we can do by updating the vaccine in terms of better binding to the spike, etc.

Hypothesis 5. Vaccination against original SARS-COV-2 triggered the dominance of delta variant. If we vaccinate most people against Delta, we may trigger the next strain to sweep, which may be even more aggressive, while only getting temporary protection.

Hypothesis 6. Supply chain woes: we'd need to throw out our stockpiles and restock with new variant vaccines.

Hypothesis 7. It's coming soon you Muppet!

Hypothesis 8. Spicy!

Hypothesis 9. Bad optics, admitting dropping efficacy.

Hypothesis 10. within-delta evolution (e.g. AY.23 or AY.4.2) means we would still be behind by the time we get the new vaccine out.

Hypothesis 11. It's over. It's going endemic, mix of natural and vaccine immunity is pushing this thing under, that's good enough, we're also getting early treatment options, and we can focus on producing enough doses for the world.

Hypothesis 12: (blackpill) the original vaccines work for the actually intended use case, which may not be exactly identical to the one being promoted.

Hypothesis 13. Diminishing returns (scroll up for the full thread by Scott, it's worth it)

Hypothesis 14. Everything is awesome. I am a conspiracy theorist. (hypothesist, but who's counting).