Thread by @BillHanage

I am seeing a lot of anxiety around partial immunity through vaccination producing selection for escape variants. Here @colinrussell and I explain why we *don't* think that's likely 1/n science.sciencemag.org/content/372/65…

It depends on the supply of the mutations that enable immune evasion. If we assume this happens during breakthrough cases in vaccinated people, there's not much time for it to make a difference, because transmission tends to happen early on in infection 2/n

And if breakthrough cases are less likely to transmit in general (as seems so in at least some cases) that makes it even more difficult 3/n papers.ssrn.com/sol3/papers.cf…

Selection is certainly a really powerful force, but it gets a helping hand from 'standing variation' meaning diversity in the population in vulnerability to the selective pressure before it is introduced - in its absence, they don't get selected. But that can change 4/n

What leads to a lot of diversity in the viral population? A lot of infections! And what is the best way to reduce infections? Vaccination! (aided and abetted by non-pharmaceutical interventions natch) 5/n

For more thorough explanation going deeper into this and considering other angles, read this from @sarahcobey @mlipsitch @DanLarremore
nature.com/articles/s4157… 6/n

I can see some questions about infections in immunocompromised individuals. I think we need to watch these extremely carefully. Not clear to me that less immunity will provide more selection, but our experience so far should lead to vigilance 7/n

And of course the best way to stop infections in the immunocompromised is to stop the virus before it can get to them! And vaccination will help with that too 8/n

Now there is still a lot of infection, but there are a lot of vaccines too (and vaccinated people). We are continuing to learn more about them including how they work against variants. That will be something to watch closely in the coming months 9/n

But for now we should remember we are in a MUCH better place than we were, that every day brings us closer to the end, and that our attention should turn to those parts of the world still struggling to get people vaccinated 10/end