CDC study shows three-fourths of people infected in Provincetown COVID-19 outbreak were vaccinated but few required hospitalization Customers wait for their orders at a Provincetown restaurant, July 20, 2021. Barry Chin / The Boston Globe By Carolyn Y. Johnson, Yasmeen Abutaleb and Joel Achenbach, Washington Post July 30, 2021 | 4:01 PM Email A sobering scientific analysis published Friday of an explosive Massachusetts covid-19 outbreak fueled by the delta variant found that three-quarters of the people who became infected were fully vaccinated. The report, from the Centers for Disease Control and Prevention, is one key piece of a growing body of evidence that bolsters the hypothesis that vaccinated people can spread the more transmissible variant and may be a factor in the summer surge of infections.