CNN  — 

Two of the biggest retail pharmacies in the U.S. are temporarily closing some stores and pharmacies on the weekends as the latest surge in Covid-19 causes staff shortages.

Walgreens (WBA) said that, like many industries, this latest surge in the Omicron variant is placing a significant strain on its business in the short-term and driving demand unlike “anything seen before.”

In a statement to CNN on Friday, Walgreens spokesperson Kris Lathan said, “While the vast majority of our stores are open and operating with normal business hours, the ongoing labor shortage combined with the surge of COVID-19 cases has resulted in isolated instances in which we’ve had to adjust operating hours or temporarily close a limited number of stores.”

When making the decision to adjust store hours, Lathan said that the company makes every effort to minimize disruption for customers by selecting days with “the lowest prescription demand.” She added that when the company temporarily closes a store, it directs some pharmacy services to the nearest open Walgreens.

CVS said on Friday that the lion’s share of its stores are operating on their normal weekend hours, according to Mike DeAngelis, executive director of CVS Corporate Communications. But he noted that “a tiny fraction of stores are temporarily closed on one or both days of the weekend to help address acute staffing issues amidst both the omicron surge and the workforce shortage affecting nearly every industry and company.”

The adjusted operating hours in these stores are temporary, he said.

Pharmacies closing because of staffing pressures is happening across the country, according to Mitchel Rothholz, chief of staff at the American Pharmacists Association.

“It’s a problem across the whole healthcare system, not just in pharmacy,” Rothholz told CNN last month, “but our members are dealing with this constantly now, because of the increased demand for testing as well as Covid vaccinations, people who are wanting to get the boosters or even getting their first doses.”

–Virginia Langmaid contributed to this report