CDC says some vaccinated Americans should wear masks indoors again

The Centers for Disease Control and Prevention recommended Tuesday that fully vaccinated Americans in parts of the country with "substantial or high transmission" of COVID-19 should return to wearing masks indoors, citing new data on the highly contagious Delta variant.

The CDC also said masks should be required of everyone inside K-12 schools while urging classrooms to return to full-time, in-person classes "with proper prevention strategies" in place. The agency recommended that all vaccinated people consider wearing a mask if someone in their household was unable to be protected by the vaccine, like those with compromised immune systems or children who are too young to receive a shot, regardless of transmission levels in their community. The new guidance comes as a growing number of local and state health officials have already returned to mandating masks indoors, with cases of the virus surging among unvaccinated Americans. Some 63% of U.S. counties currently have a "high" or "substantial" spread of the virus, according to the CDC.