Drugstore chain Walgreens Boots Alliance Inc said on Wednesday it had administered more than 29 million COVID-19 vaccines at its stores so far, led by a surge in parts of the United States that had lagged in vaccinations.

Vaccine administration rose more than 30% in states such as Alabama, Florida, Georgia, Kentucky and Texas in the past few weeks, the company said.

Cases of COVID-19, along with hospitalizations and deaths from it, increased in the U.S. last week, even as the pace of vaccinations increase amid concerns over the highly contagious Delta variant.

One in three cases nationwide occurred in Florida and Texas in the past week, health officials said on Monday.

Walgreens, among the largest U.S. pharmacy chains, said in June it expects to administer 28 million vaccines this year.

The company said on Wednesday it had made masks mandatory for its U.S. employees and required staff working at the country's support offices to be fully vaccinated.

Walgreens became the latest company to update its policies as COVID-19 cases rise in the United States.

New guidance from the U.S. Centers for Disease Control and Prevention that recommends fully vaccinated individuals wear masks, as well as surging cases due to the Delta variant, have led companies to rethink their policies.

Walgreens said it encouraged customers, including those who are vaccinated, to wear masks. The company added that the vaccination mandate, which requires employees to be inoculated by Sept. 30, does not apply to U.S. employees working in its stores, distribution centers or other facilities.

Rival CVS Health Corp said employees at its worksites were required to wear masks or face covers, regardless of their vaccination status.

Tyson Foods Inc, Microsoft Corp and Detroit's Big Three automakers also updated their vaccination and masking policies on Tuesday.

(Reporting by Manas Mishra in Bengaluru; Editing by Saumyadeb Chakrabarty and Shounak Dasgupta) ((Manas.Mishra@thomsonreuters.com; www.twitter.com/Manasmishra24; within U.S. +1 646 223 8780, outside U.S. +91 806749 2709))