Last I checked 3% of deaths are among vaccinated people. That isn't what "almost zero" looks like. It's really good but it aint zero. Next up with 58% of the population not being fully vaccinated yet we have plenty of opportunity for problems if we don't take the ball all the way to the end zone especially with vaccinated people not being exactly evenly distributed.

I give you the fine state of Mississippi where only 1/3 is vaccinated and they are only doing 15k vaccinations per week. If the population even wanted a vaccine at this rate it would achieve immunity some time in 2023. Its like a nice little virus lab where there are plenty of unvaccinated hanging around for existing strains but the first strain to successfully attack vaccinated will gain a huge advantage.

https://msdh.ms.gov/msdhsite/_static/resources/12130.pdf