We DO have a high vaccination rate...64.07% fully vaccinated. But part of the problem is out-of-state people came from all over to celebrate the 4th. The ENTIRE population of P-town is only 2994 people.
So I just read a Twitter thread, that tries to explain what happened in Cape Cod. First, this cluster still correctly identified the flaw in the assumption that vaccinated people don't spread COVID, but there are some features of this cluster that have implications for the potential within the general population.
85% of the cases were in men. This does not mean men are more at risk for being infected with COVID after vaccination. It means more men, in P-town were present and engaging in behavior that leads to greater chances of being infected, and the CDC was trying to avoid the negative framing that would undoubtedly accompany this cohort.
You seem to be familiar with the area. What is unique to the gathering in P-town?
Don't go around kissing people who might be infected with COVID. So the same rules from throughout this pandemic apply... Close contact increases the potential for infection, even when vaccinated and some behaviors increase how close, the close contact is.
So we do have to worry about vaccinated people spreading, but it's not going to be the same level of spread (and thus the point of the twitter thread is that the CDC is overestimating the increase in R(0) as it would be in the general population) as seen in P-town; as many people aren't getting that much action.
So hopefully, this will help you relax a little about what it means overall. But Sturgis will probably be another fun time for the Dakotas and surrounding states.