Walgreens Boots Alliance will close nearly all of its stores and pharmacies on Thanksgiving Day for the first time in the chain's history to give staff "time with their loved ones," the company said Thursday.

The closures of most of its over 8,700 stores next Thursday come at a time when the second-largest U.S. pharmacy has faced criticism from its pharmacists and technicians over poor work conditions and under-staffing.

"We have consistently heard from our team members — who are the face of Walgreens — that time off is a meaningful way for us to demonstrate we value them," said Tracey Brown, president of Walgreens Retail and chief customer officer.

However, nearly all of its 700 24-hour locations will remain open on Thanksgiving, along with certain distribution centers and other sites including supply chain and centralized teams, Walgreens said.

Many big box stores such as Walmart and Target are closed on Thanksgiving, but pharmacies and grocery stores typically remain open with adjusted hours.

Pharmacy chains CVS Health and RiteAid did not immediately respond to Reuters requests for comment on their Thanksgiving staffing plans.

Many pharmacists and technicians in the U.S. have been trying to unionize with support from the IAM Healthcare union.

Some employees at CVS and Walgreens' U.S. pharmacies had launched a three-day walkout from Oct. 30 to push the companies to improve working conditions and add more staff to their stores.

However, CVS and Walgreens had said the work action had minimal impact on their operations, with most stores remaining open.