Posted: Oct 06, 2021 11:50 am
I don't know about airborne transmissibility, but transmissibility generally is one of the fitness gradients along which evolution is directed.
In general, in a population with a degree of immunity and all the attendant gradients, this occurs either by resisting the vaccine better and pushing the window of transmissibility open by being infectious for longer, or by reaching peak infectiousness much earlier compared to first symptoms. The vaccine reduces the window at both ends for alpha, but it seems not to have the same effect on the beginning of the window for delta, because it reaches peak infectiousness (and symptoms) much earlier.
In general, in a population with a degree of immunity and all the attendant gradients, this occurs either by resisting the vaccine better and pushing the window of transmissibility open by being infectious for longer, or by reaching peak infectiousness much earlier compared to first symptoms. The vaccine reduces the window at both ends for alpha, but it seems not to have the same effect on the beginning of the window for delta, because it reaches peak infectiousness (and symptoms) much earlier.