(Bloomberg) -- Starbucks Corp. is instructing employees to use the three-ply medical-grade masks it provides instead of cloth facial coverings, changing its prior guidance amid a wave of omicron infections.

“Cloth masks are not as effective against omicron,” Starbucks said in a memo to U.S. district managers on Jan. 18. In addition to the medical-grade masks, employees can wear N95, KN95 or KF94 face coverings, but the company isn’t providing those due to supply constraints. The coffee chain said it updated guidance at its 15,000 U.S. locations after reviewing the latest recommendations from the U.S. Centers for Disease Control and Prevention. 

With the recent surge of Covid-19 infections, restaurants and retailers are struggling to keep their stores staffed and running as more workers call off sick. In some cases, operators close dining rooms and shift to takeout and drive-thru only due to a dearth of workers. Denny’s Corp. recently said it periodically turned off its delivery orders because there weren’t enough people to prepare meals. 

Seattle-based Starbucks, which renewed calls for employees to get booster shots, altered its self-isolation policy as well. Staff should now stay home if exposed to Covid-19, regardless of vaccination status and even if they’re not ill. 

That temporary directive is a departure from CDC guidance, which says that fully vaccinated individuals exposed to the virus don’t have to self-isolate if they’re not having symptoms. Starbucks said it is “going above and beyond that after hearing from partners who were concerned.”

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