Even if all of Provincetown residents were vaccinated that would not imply that anywhere near the majority of the people currently in Provincetown were vaccinated. I'm not sure how we can usefully estimate the vaccination rate of the people who have been in Provincetown recently. Google says the vaccination rate for Massachusetts is about 72%. That seems really worrying to me because if that vaccination rate describes the people in Provincetown then the infection rate implies that the vaccine is offering no real protection - i.e. 75% of population vaccinated and 75% of infected were vaccinated.
i don't think it was neglected, as it is more like obvious thing wasn't explicitly stated - as vaccine obviously not increasing infection chances, 3/4 of infected being vaccinated means that vaccination rate >= 3/4, and that pretty much means "essentially the whole town is vaccinated"
https://www.masslive.com/capecod/2021/07/how-provincetown-ac...
Despite virtually everyone in the town being vaccinated, 25% of the cases in the outbreak were in the remaining handful of unvaccinated people! As more areas reach close to 100% vaccination, we will start to see weird quirks of statistics like this more often, but if your takeaway here is that it's really easy for vaccinated people to catch and spread COVID, you're very wrong. Breakthrough infections are prevented by vaccines like Pfizer with about 99% efficacy, and without a breakthrough infection there is no transmission. If pretty much everyone were vaccinated, the odds of transmission would go to zero very rapidly.