Masks and COVID

Mask requirements are back in many parts of the country – even for people who’ve been fully vaccinated against COVID-19. The CDC last week said that COVID infections due to the Delta variant of the virus are increasing enough to warrant masks in public places where transmission rates are high. How do you know if that applies in your community? And what good will it do if vaccinated people start wearing masks again, anyway? Peter Chin-Hong is an infectious disease specialist and professor of medicine at the University of California – San Francisco. (Matt O’Brien/AP Photo)