Reversing a decision made just two months ago, the Centers for Disease Control and Prevention is expected to recommend Tuesday that people vaccinated against the coronavirus return to wearing masks indoors in certain areas of the country.
The change follows reports of increasing breakthrough infections with the Delta variant of the virus in fully vaccinated individuals and increases in cases in regions with low vaccination rates. The vaccines remain effective against the worst of the consequences of infection with the virus, including those that involve the Delta variant.
But the new guidelines, the details of which are expected later Tuesday, would mean a sharp turn from the agency’s position since May of eliminating the need for vaccinated individuals to wear masks in most indoor spaces.
As recently as last week, an agency spokesman said the CDC had no plans to change its guidelines unless there was a major change in science. Federal officials met on Sunday evening to review new evidence that may have led to the reversal, CNN reported Tuesday.
“I think that’s great,” said Dr. Celine Gounder, an infectious disease specialist at Bellevue Hospital Center in New York. Based on what scientists are learning about the Delta variant’s ability to cause breakthrough infections, she said, “This is a step in the right direction.”
White House press secretary Jen Psaki said at a news conference Tuesday that a change in guidelines is vital to “fighting an ever-evolving virus” and that the CDC is right to do so. The agency is scheduled to hold a press conference at 3:00 p.m. Eastern time.
“Your job is to examine evolving information, data and an evolving historical pandemic and provide guidance to the American public,” Ms. Psaki said. “That’s exactly what they’re going to do, and they’ll be giving specific details on that later that afternoon.”
The CDC’s first guidance in May said people fully protected from the coronavirus could stay mask-free indoors in most scenarios, but recommended that unvaccinated people continue to wear masks. These recommendations were harshly criticized by some experts who said it was premature given the large numbers of unvaccinated people in the country.
Dr. Rochelle Walensky, the director of the CDC, pointed to two scientific findings as essential factors at the time. Few vaccinated people become infected with the virus, and transmission seems to be even rarer, she noted; and the vaccines appear to be effective against all known variants of the coronavirus.
The day after the announcement, the agency released results from a large study showing that 94 percent of those who received two doses and 82 percent of those who received two doses of Pfizer-BioNTech and Moderna’s mRNA vaccines were effective in preventing symptomatic disease. that they had received were effective at one dose.
Understand the state of vaccine mandates in the United States
But that data and the CDC’s decision were based on infections from previous versions of the virus before the Delta variant crossed the country. Reports of clusters of infection in fully immunized individuals suggest that the variant may break the vaccine barrier more often than previous iterations of the virus.
On Sunday, Dr. Anthony S. Fauci, Chief Medical Advisor to President Biden, told CNN State of the Union that the pandemic is “going in the wrong direction” because too many Americans are not being vaccinated. According to the federal government, a little less than half of the population was fully vaccinated by Monday.
Dr. Fauci said the use of masks by vaccinated individuals is being “actively considered” by federal health authorities, adding that it is advisable for vaccinated individuals to wear masks indoors in areas with “high infection dynamics”.
Daniel E. Slotnik contributed the reporting.