CDC said:COVID-19 vaccines are effective at preventing severe disease, hospitalization, and death. However, since vaccines are not 100% effective at preventing infection, some people who are up to date with the recommended vaccines will still get COVID-19. This is called a breakthrough infection.
I am not a medical expert like all the people reading news reports these days. I noticed a nuanced change in messaging from CDC several months or longer ago. The covid vaccine was repositioned as not preventing infection, but preventing death and hospitalization.
A finding that people getting most vaccines were most infected, may be an innocent correlation if most at risk people are who are most likely to get vaccinated.
JR