The US Centers for Disease Control and Prevention (CDC) is set on Tuesday to recommend fully vaccinated Americans wear masks indoors in at least some instances, as the more highly transmissible Delta variant of the coronavirus has led to a surge in infections, sources said.
That would mark a reversal of the CDC's announcement in May that prompted millions of vaccinated Americans to shed their face coverings.
The CDC will announce revised mask guidance but the specifics of when the agency will recommend fully vaccinated Americans wear masks indoors are not fully clear, the sources said. The recommendations to wear masks in some indoor settings will apply in areas with surging Covid-19 cases, they said.
The CDC and White House declined to comment. The CDC said it plans a 3 p.m. (1900 GMT) Covid-19 update media briefing.
In May, the CDC advised that fully vaccinated people do not need to wear masks outdoors and can avoid wearing them indoors in most places, guidance the agency said would allow life to begin to return to normal.
The CDC also said in May that fully immunized people would not need to physically distance in most places.
The United States leads the world in the daily average number of new infections reported, accounting for one in every nine infections reported worldwide each day. The seven-day average for new cases is rising sharply and now at 57,126, still about a quarter of the pandemic peak.
On Monday, the Biden administration confirmed it will not lift any existing international travel restrictions, citing the rising number of cases and the expectation that cases will continue to rise in the weeks ahead.
CDC Director Rochelle Walensky said in May that the new guidance was based on a sharp reduction in cases, expansion of vaccines to younger people, and vaccine efficacy against coronavirus variants.
At the time, it still recommended vaccinated people wear masks on planes and trains, and at airports, transit hubs, mass transit and places like hospitals and doctor's offices.
Top US infectious disease official Anthony Fauci said on Sunday on CNN that health officials were considering whether to revise mask guidance for vaccinated Americans, saying it was "under active consideration."
Masks became a political issue in the United States with then-President Donald Trump resisting mandating face coverings while President Joe Biden embraced masks and mandated them for transit hubs days after taking office.
Some US states issued aggressive mask mandates while others declined to do so or dropped them months ago.
The new CDC recommendations are not binding and many Americans, especially in Republican leaning states, may choose not to follow them.
Earlier this month, the CDC updated its guidance for US schools reopening in the fall, recommending masking indoors for everyone who is not fully vaccinated against Covid-19 and three feet (1 meter) of distance within classrooms.
The CDC said school administrators can require indoor mask use even for students and educators who are vaccinated, depending on the needs of the community.