By Marie Rosenthal, MS

The CDC updated its mask guidance recommending that everyone wear a mask indoors in public places regardless of vaccination status if they are in an area with substantial or high transmission.

The CDC also recommended universal indoor masking for all teachers, staff, students and visitors to kindergarten through 12th grade schools, regardless of vaccination status, until vaccines are authorized and widely available to all children and vaccination rates are sufficient to control transmission. This is a change to recommendations just released earlier this month, but she said it was necessary to enable in-person learning.

“This pandemic continues to pose a serious threat to the health of all Americans,” said Rochelle P. Walensky, MD, MPH, the director of the CDC.

She said new science about the Delta variant led to the update. “I have seen new scientific data from recent outbreak investigations showing that the Delta variant behaves differently from past strains of the virus that causes COVID-19,” Dr. Walenksy said.

Although the COVID-19 vaccines still reduce the risk for serious disease, hospitalization and death, vaccinated people with breakthrough infection can transmit the virus to others.

“We continue to estimate that the risk of a breakthrough infection with symptoms upon exposure to the Delta variant is reduced by sevenfold, and the reduction is 20-fold for hospitalizations and death,” she said, but the viral load in a vaccinated person with breakthrough infection is similar to an unvaccinated person, so some can still spread the virus to others.

“Vaccinated individuals continue to represent very small amounts of transmission occurring around the country,” she said, emphasizing that most of the serious cases are among unvaccinated individuals and urged them to be vaccinated.

“I think we still largely are in a pandemic of the unvaccinated. The vast majority of severe disease, hospitalization and death is almost exclusively happening among unvaccinated people, which is why we so very much want to double-down” on making sure people are vaccinated, Dr. Walensky said.

“We strongly encourage everyone to get vaccinated. Getting vaccinated continues to prevent severe illness, hospitalization and death. Even with Delta, it also helps reduce the spread of the virus in our communities,” Dr. Walensky said.

The Infectious Diseases Society of America (IDSA) issued a statement supporting the change in guidance.

“To stay ahead of the spread of the highly transmissible Delta variant, IDSA also urges that in communities with moderate transmission rates, all individuals—even those who are vaccinated—wear masks in indoor public places,” said Barbara D. Alexander, MD, MHS, FIDSA, the president of the IDSA.

“Unfortunately, vaccination rates in most U.S. communities remain far too low to minimize COVID-19 transmission, and it is impossible in public settings to know who is vaccinated and who is not. Vaccination coverage remains below 40% in over half of the counties in the country, and 63% of U.S. counties have high or substantial virus spread, according to CDC. As a result, successful community mitigation measures should be based on local transmission rates, not the vaccine status of individuals,” Dr. Alexander said in the statement.