What the new CDC mask guidelines mean for Massachusetts Several counties in the state have COVID-19 transmission rates at levels at which the CDC says even fully vaccinated individuals should be wearing masks indoors. A mix of visitors Tuesday — some wearing masks, some not — at Faneuil Hall Marketplace and Quincy Market in Boston. Craig Walker / The Boston Globe Email Amid a national spike in COVID-19 cases driven by the highly contagious Delta variant, the Centers for Disease Control and Prevention released new guidance Tuesday recommending that everyone in virus hotspots once again wear masks indoors, regardless of their vaccination status.