The Centers for Disease Control and Prevention updated its masking guidance Tuesday, recommending that everyone, whether they are vaccinated or not, wear a mask indoors in places where the coronavirus is spreading widely. The change was met with relief from experts who said masking up again is essential to combat the highly contagious delta variant.
"We know masks work, and they work against every variant that this virus has produced," said Ali Mokdad, a professor of global health at the University of Washington. "If we use them, they will save lives, save livelihoods and prevent us from shutting down our economy."
The CDC's updated recommendations come as a devastating fourth wave of infection is sweeping the nation. Cases are rising in every state, with hospitalizations surging in states with low vaccination rates, such as Missouri, Arkansas, Mississippi and Florida.
While the majority of the outbreaks are happening among unvaccinated individuals, wearing a mask regardless of vaccination status can protect the entire community, Mokdad said. And while the CDC's guidance focused on areas where the virus is spreading widely, Mokdad urged people everywhere to take precautions.
"The whole country is on fire," he said. "Covid-19 is rising in every state. We're dealing with a stubborn, aggressive variant and we all need to be very careful."
The CDC's new recommendation comes less than three months after the agency said masks and social distancing are no longer necessary for people who have been fully vaccinated against Covid-19. The change in guidance was driven by the delta variant's higher transmissibility and new evidence from the CDC that in rare cases, fully vaccinated individuals who get infected with the variant can spread the virus just as easily as unvaccinated people.
"This new science is worrisome and unfortunately warrants an update to our recommendations," CDC Director Rochelle Walensky said Tuesday in a news briefing.
Dr. Kartik Cherabuddi, an infectious diseases physician and epidemiologist at the University of Florida, said the CDC was right to alter its guidance to reflect the changing situation on the ground. As the pandemic evolves further, the public should be prepared to make other changes, if necessary.
"You have to look at it as dynamic," Cherabuddi said. "All of these factors — medical, social, economic impacts — get taken together to keep the guidance dynamic."
In discussing the updated recommendations, Walensky said the Covid-19 vaccines continue to do "an exceptional job" of protecting people from severe illness, hospitalization and death. The CDC has found, however, that in rare breakthrough infections — instances where a fully vaccinated person tests positive for the virus — the amount of virus in that vaccinated person's system is similar to the viral load in an infected individual who is unvaccinated.
The finding suggests some fully vaccinated people who get infected with the delta variant could be highly contagious, potentially putting children too young to get vaccinated, immunocompromised individuals and otherwise unvaccinated people at risk. The CDC's guidance included recommendations that all students in kindergarten through 12th grade should wear masks when they return to classrooms for the new school year.
"If that indeed means that vaccinated people can become a source of transmission, though not the majority of transmission, mask use is a good idea," said Ajay Sethi, an epidemiologist and associate professor of population health sciences at the University of Wisconsin-Madison.
Not everyone was convinced that uniform indoor masking will have a big effect on slowing transmission. In an interview Wednesday with NPR's Morning Edition, Dr. Scott Gottlieb, former FDA commissioner and a Pfizer board member, said fully vaccinated people need to understand that they are not impervious to infection, but also questioned the decision to ask them to mask up again.
"I think at this point, where we are with this delta wave — which is probably closer to the end than the beginning — and the fact that probably a very small percentage of the transmission is occurring among vaccinated people, I don’t know how prudent this is and practical it is," Gottlieb told NPR.
He said that vaccinated individuals should remain cautious around young children and other vulnerable adults, but added that asking everyone who is vaccinated to wear a mask again will likely be "very little bang for our buck in terms of trying to reduce transmission right now."
Other experts have been critical of the CDC, saying the agency was premature in lifting its mask mandate for fully vaccinated people in May. Mokdad has been vocal on Twitter, saying the agency needed to reimpose its masking guidance earlier, particularly before the delta variant became the predominant strain circulating in the country.
"You don't wait until you have a major surge in every state in the country to reverse it," he said. "They should have reversed it earlier, but I'm still glad they did it now. It's very important."
Andy Slavitt, the former lead White House adviser on the country’s Covid-19 response, acknowledged critiques that the CDC has been slow to act, saying on Twitter that the agency must take a measured approach.
"Are there people who have been ahead of the CDC in calling for this? Yes, and there always will be," Slavitt tweeted Tuesday. "Why? Because those of us on Twitter don’t have to live with the results of our recommendations. Th[e] CDC does."
Sethi agreed that the CDC is often in a tough position because of all the considerations that go into its official guidance.
"They're balancing delivering scientifically based recommendations with the sentiment of a public that is just tired of the pandemic and wants it to go away," he said.
Still, while masks will be critical to slowing the spread of the delta variant, experts said it's important to also focus on increasing vaccine uptake across the country.
Roughly 49.7 percent of eligible people in the United States are fully vaccinated against Covid-19, but vaccination rates vary widely between states and within individual counties. Ramping up vaccinations in states that are lagging behind will be key to turning a corner in the pandemic, Cherabuddi said.
"This is definitely a critical point where we have to improve our vaccination rates," he said. "The vaccines are the only thing that will truly get these numbers down."