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Perspective from Gitanjali Pai, MD

Press Conference.

Disclosures: Del Rio and Walensky report no relevant financial disclosures.
July 27, 2021
1 min read

CDC alters mask guidance, says even vaccinated Americans need them in some places

Perspective from Gitanjali Pai, MD

Press Conference.

Disclosures: Del Rio and Walensky report no relevant financial disclosures.
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The CDC altered its mask guidance Tuesday to say that even vaccinated people should wear them indoors in areas with high coronavirus transmission, and that everyone should wear masks indoors in K-12 schools regardless of vaccination status.

CDC Director Rochelle P. Walensky, MD, MPH, attributed the updates to “new science” showing that vaccinated people who are infected with the delta variant of SARS-CoV-2 may be able to spread the virus.

Source: Adobe Stock.
The CDC said even vaccinated Americans should start wearing masks again indoors in areas of the U.S. with high transmission. Source: Adobe Stock.
Rochelle P. Walensky

“This new science is worrisome and unfortunately warrants an update to our recommendations,” Walensky said in a press briefing.

The updated guidance came 2 1/2 months after the CDC said fully vaccinated Americans no longer had to wear masks or socially distance indoors, and just weeks after it recommended that only unvaccinated people needed to wear masks indoors at all times in schools.

According to CDC data, the United States recorded more than 66,700 new cases of COVID-19 on July 22, up from about 13,600 cases reported on June 22. There also has been a decline in the rate of vaccination from a peak of more than 3 million doses administered daily in April to less than 500,000 per day currently. As of Tuesday, less than 58% of the eligible population was fully vaccinated.

The new guidance for fully vaccinated people recommends that they wear masks indoors in areas of the country with “substantial” or “high” transmission — defined as 50 to 100 cases per 100,000 people over a 7-day period for “substantial” transmission and 100-plus cases per 100,000 people over a 7-day period for “high” transmission, Walensky noted. The guidance was published in MMWR.

Carlos del Rio

“This is the right call,” Carlos del Rio, MD, executive associate dean at Emory University School of Medicine, told Healio. “With increasing transmission, masking indoors for both vaccinated and unvaccinated is the right move. This is an evolving pandemic, and we need to adapt our recommendations in response to the data.”

A color-coded, county-level map kept by the CDC shows that some states, including many in the Midwest and South, are mostly orange or red — the colors representing “substantial” and “high” transmission — suggesting that vaccinated people in those states would largely fall under the new CDC guidance.

“The delta variant is showing every day its willingness to outsmart us and to be an opportunist in areas where we have not shown a fortified response against it,” Walensky said, noting that 80% of sequenced SARS-CoV-2 samples now contain the variant, which was first identified in India.

Walensky said she has seen data from outbreak investigations in several states and other countries “showing that the delta variant behaves uniquely differently from past strains of the virus that cause COVID-19” — namely, that vaccinated people infected with delta may be contagious and spread the virus.

However, she noted that vaccination continues to prevent severe illness, hospitalization and death from COVID-19, even among people infected with the delta variant.

“It also helps reduce the spread of the virus in our communities,” she said. “Vaccinated individuals continue to represent a very small amount of transmission” and their risk for an infection accompanied by symptoms “is reduced by several fold.”

The updated CDC guidance is part of a raft of stricter measures and recommendations that have recently taken aim at halting the uptick in cases and stamping out vaccine hesitancy, including a push to mandate vaccination for health workers and public employees.

President Joe Biden called the updated CDC guidance “another step on our journey to defeating this virus.”

“I hope all Americans who live in the areas covered by the CDC guidance will follow it; I certainly will when I travel to these areas,” he said in a statement.

The Infectious Diseases Society of America also supported the changes, saying that vaccination rates in most areas of the U.S. are too low to minimize transmission and that “it is impossible in public settings to know who is vaccinated and who is not.”

“The overwhelming majority of current COVID-19 cases are occurring in unvaccinated individuals, and significantly increasing vaccination rates are urgently needed to stop the spread of COVID-19 and save lives,” the IDSA said in a statement. “Until then, mask wearing will help reduce infections, prevent serious illnesses and death, limit strain on local hospitals and stave off the development of even more troubling variants.”


CDC. Trends in number of COVID-19 cases and deaths in the US reported to CDC, by state/territory. Accessed July 27, 2021.

CDC. Trends in number of COVID-19 vaccinations in the US. Accessed July 27, 2021.

Christie A, et al. MMWR Morb Mortal Wkly Rep. 2021;doi:10.15585/mmwr.mm7030e2.