Fully vaccinated people should go back to wearing masks indoors in counties with “high” or “substantial” COVID-19 infections, the CDC announced on Tuesday. That’s now 63% of counties in the US.
The recommendation partly reverses a May CDC guidance that said fully vaccinated individuals could “resume activities that you did before the pandemic without wearing a mask or physically distancing.” The change comes as the highly contagious Delta variant causes COVID-19 outbreaks nationwide, overwhelmingly driven by people who have chosen not to get vaccinated. But the CDC said the new change was motivated in large part by new data showing that vaccinated individuals who get infected by Delta — so-called breakthrough cases — could also transmit the virus.
The new guidelines also reverse recommendations from the health agency released earlier this month, urging all schools to reopen for in-person learning in the fall. While the previous guidance said teachers, staff, and students who were vaccinated did not need to wear masks, the new recommendations urge universal masking regardless of vaccination status. Last week, the American Academy of Pediatrics pushed back against the CDC’s guidance, pressing for universal masking in schools.
“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,” CDC head Rochelle Walensky said at a press conference announcing the guidance on Tuesday.
"This was not a decision taken lightly," Walensky added. "It is not a welcome piece of news that masking is going to be part of people's lives who have already been vaccinated."
The change comes as the CDC has faced mounting pressure to reconsider its mask guidance, which assumed that unvaccinated individuals would continue to mask up indoors as most businesses and restaurants fully reopened and that they would be incentivized to get their shots in order to ditch their masks.
Instead, vaccination rates have continued to drop and Delta has caused a surge in infections across the country. One preliminary study suggested that people infected with the Delta variant can shed roughly 1,000 times as many viral particles than what was seen with the original coronavirus, leading to what Walensky has called a “pandemic of the unvaccinated.”
But on Tuesday, Walensky said the change was also motivated by concerning new data showing that breakthrough infections, while rare, might also be contagious.
The vast majority of people who get breakthrough infections will be protected from severe illness and death. The mRNA vaccines most widely used across the US appear almost as effective in preventing infections against the Delta variant as they do the original coronavirus, around 88% effective against infection and 96% effective against severe illness. But Walensky said the new data on breakthrough cases being infectious was concerning.
“This new science is worrisome and unfortunately warrants an update to our recommendations,” Walensky said.
Now responsible for more than 83% of US cases, the variant has driven new outbreaks threatening hospitals in undervaccinated states such as Missouri and Arkansas, and in smaller clusters everywhere from Florida to California. Almost half of US counties are seeing “high” transmission rates — a 17% increase from last week — and another 17% are seeing “substantial” ones, according to CDC data.
Some scientists and public health experts lauded the CDC’s changes in light of the increased risk across the country.
“The Delta variant is clearly more transmissible than any preceding strain,” said vaccine expert Joel Ernst of the University of California, San Francisco. “The best protection comes from using multiple measures at one time: vaccines, masks, and distancing.”
American Academy of Pediatrics President Lee Savio Beers said her organization supported the CDC's change. She said there was tremendous frustration among pediatricians about low COVID-19 vaccination rates among adults in places with outbreaks, since children under 12 aren't even eligible for the shots. "We are seeing kids get terribly sick, and those kids are seeing family members get sick," Beers said.
But other public health experts criticized both the timing and scope of the CDC recommendations.
“We are essentially punishing the vaccinated,” said infectious disease expert Amesh Adalja of the Johns Hopkins Bloomberg School of Public Health, who said the time has come for vaccine mandates in workplaces and schools. “The unvaccinated, by choice, are a threat to public health at this point.”
“What is going to happen is that vaccinated people in highly vaccinated places without outbreaks are going to go back to wearing masks everywhere, and people in other places won’t, because they don’t want to,” he added. Schools should mandate vaccinations for teachers, he added, like they require shots for students.
National Education Association President Becky Pringle, head of the largest teachers’ union in the US, said 86% of her members have received at least one shot, and that the group supports universal masking in schools. However, “vaccinations may not be a viable option for all who are eligible,” she said by email, calling for “providing educators the option to take regular COVID-19 tests in lieu of vaccination.”
The new recommendations could cause further confusion because they lack recommendations for outdoor gatherings, restaurants, bars, and offices, said public health communication expert Matthew Seeger of Wayne State University.
The rollout of the new CDC recommendations was also a problem, he added by email. Walensky had defended the May recommendations last week, saying that local communities could decide to call for stricter guidelines if warranted. “Whenever there are conflicting messages — for whatever reasons — the effectiveness and credibility of the message may be undermined,” said Seeger.
President Joe Biden commended the CDC for its new guidance in a statement on Tuesday, saying, "Today’s announcement by the CDC—that new research and concerns about the Delta variant leads CDC to recommend a return to masking in parts of the country—is 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."
Biden also added that the new guidance made it urgently clear that more people in the US need to get vaccinated. Nearly 57% of people in the US have received at least one COVID-19 vaccine. "Today’s announcement also makes clear that the most important protection we have against the Delta variant is to get vaccinated," he said. "Although most U.S. adults are vaccinated, too many are not. While we have seen an increase in vaccinations in recent days, we still need to do better.