“If a member has a medical condition that prevents them from wearing a mask, they must wear a face shield at Costco,” Chief Executive Craig Jelinek said in a letter to members Thursday.

The new rules will apply to all but children under 2.

“This updated policy may seem inconvenient to some, however we believe the added safety is worth any inconvenience,” Jelinek said. “Our goal is to continue to provide a safe shopping environment for our members and guests, and to provide a safe work environment for our employees.”

Mask mandates have become a political hot potato in parts of the country, but public health experts have urged face masks as a simple yet effective way of curbing the spread of COVID-19.

Earlier this week, the U.S. Centers for Disease Control and Prevention strengthened its face-mask recommendation, saying studies show masks protect the wearer too, whereas before masks had been seen more as a way to protect others.

Costco’s new policy comes as new coronavirus cases are surging throughout the country, with more than 160,000 new cases Thursday, according to New York Times data, another grim record.

Since the start of the pandemic, the U.S. has reported more than 10.5 million coronavirus cases, with more than 242,000 deaths, both the most in the world, according to data from Johns Hopkins University.

Costco sales have surged as consumers stock up on food and supplies while staying at home due to coronavirus restrictions, with October sales rising 16% from the previous year. Costco shares are up 28% year to date, compared to the S&P 500’s SPX, -0.99% 9.5% gain.