The majority of U.S. counties — 69.3 percent — had a high or substantial level of community COVID-19 transmission as of July 27, according to CDC data.
The data is presented in a color-coded map, detailing community transmission level data for each U.S. county.
About 52 percent of counties had high transmission, meaning there were more than 100 new infections per 100,000 people in the seven days prior. About 17 percent of counties had substantial community transmission, meaning there were at least 50 new cases per 100,000 people in the week prior.
The CDC's July 27 updated mask guidance recommends all people, regardless of vaccination status, wear a mask in indoor public spaces when in an area of substantial or high COVID-19 transmission.
The seven-day average for new cases in the U.S. as of July 29 was 71,621, marking a 151 percent 14-day increase, according to data from The New York Times. The highly transmissible delta variant, first detected in India and now the dominant U.S. strain, has largely driven the nationwide surge.