> Let's also say that it is somewhat effective against the variant so the performance of the vaccinated immune system is actually better than the naive immune s

> Let's also say that it is somewhat effective against the variant so the performance of the vaccinated immune system is actually better than the naive immune system. This is begging the question. > Because of the selection effect, you could have a higher variant prevalence compared to regular COVID-19 in the vaccinated population They are measuring the prevalence of the variant between vaccinated and control groups of similar size, not the share of variants within the vaccinated groups.