In theory if enough people have enough immunity you can explain any advantage with immune escape. I can’t rule it out. However, I’m skeptical, primarily because if everyone was previously infected then you wouldn’t see vaccines giving much advantage vs. infection (either by Omicron or Delta) or protection against severe disease. The fact that vaccines or being infected still matters vs. baseline population puts a not-too-high cap on how many people have already been infected, which in turn makes the current doubling times very hard to explain with evasion alone.
Trevor Bedford gets into this, and the short answer is technically yes, but the important part about decomposing Rt is not the decomposing it per se but the info it yields on how much vaccine escape might be going on. For reasonable R0s, there has to be substantial vaccine escape. https://twitter.com/trvrb/status/1466076797670363140
Can immune escape by itself explain the transmission advantage or do we also need it to be spreading better?
In theory if enough people have enough immunity you can explain any advantage with immune escape. I can’t rule it out. However, I’m skeptical, primarily because if everyone was previously infected then you wouldn’t see vaccines giving much advantage vs. infection (either by Omicron or Delta) or protection against severe disease. The fact that vaccines or being infected still matters vs. baseline population puts a not-too-high cap on how many people have already been infected, which in turn makes the current doubling times very hard to explain with evasion alone.
Trevor Bedford gets into this, and the short answer is technically yes, but the important part about decomposing Rt is not the decomposing it per se but the info it yields on how much vaccine escape might be going on. For reasonable R0s, there has to be substantial vaccine escape. https://twitter.com/trvrb/status/1466076797670363140