When revising its mask guidance this week to urge even vaccinated people to wear masks indoors in much of the country, the Centers for Disease Control and Prevention was criticized for not citing data in making that move.
Now it has — and the data is sobering.
The study details a COVID-19 outbreak that started July 3 in Provincetown, Mass., involving 469 cases. It found that three-quarters of cases occurred in fully vaccinated people. Massachusetts has a high rate of vaccination: about 69% among eligible adults in the state at the time of the study. . . .