The Centers for Disease Control and Prevention will recommend that vaccinated Americans wear masks indoors in places with high COVID-19 transmission rates.

From CNN:

People in areas with high or substantial Covid-19 transmission should resume wearing masks, the CDC is expected to say, according to sources familiar with the announcement. Nearly two-thirds of US counties have high or substantial transmission of Covid-19, according to CDC data; 46% of counties have high transmission and 17% have substantial transmission.

“The new guidance, the details of which are expected later Tuesday, would mark a sharp turnabout from the agency’s position since May that vaccinated people do not need to wear masks in most indoor spaces,” reports The New York Times.

CNBC adds: “The updated guidance comes ahead of the fall season, when the highly contagious delta variant is expected to cause another surge in new coronavirus cases and many large employers plan to bring workers back to the office.”

“Nobody wants to go backward but you have to deal with the facts on the ground, and the facts on the ground are that it’s a pretty scary time and there are a lot of vulnerable people,” Robert Wachter, chairman of the department of medicine at the University of California, San Francisco, told The Washington Post. “I think the biggest thing we got wrong was not anticipating that 30 percent of the country would choose not to be vaccinated.”

More from CNBC:

Federal health officials still believe fully vaccinated individuals represent a very small amount of transmission, according to the sources. Still, some vaccinated people could be carrying higher levels of the virus than previously understood and potentially transmit the virus to others, they said.