According to UK statistics breakthrough cases are not rare - the majority of newly infected are now those previously vaccinated, per capita even. As for reduct

According to UK statistics breakthrough cases are not rare - the majority of newly infected are now those previously vaccinated, per capita even. As for reduction of adverse symptoms it's unknown since deaths of vaccinated vs unvaccinated within 30 days of COVID is tracked, but not how many deaths occur within 30 days of vaccination for comparison.