Apple Inc (AAPL.O) will require retail and corporate employees to provide proof of a COVID-19 booster shot, The Verge reported on Saturday, citing an internal email.

Starting Jan. 24, unvaccinated employees or those who haven't submitted proof of vaccination will need negative COVID-19 tests to enter Apple workplaces, the report said. The Verge said it was not immediately clear if the testing requirement applies to both corporate and retail employees.

"Due to waning efficacy of the primary series of COVID-19 vaccines and the emergence of highly transmissible variants such as Omicron, a booster shot is now part of staying up to date with your COVID-19 vaccination to protect against severe disease," the memo read, according to The Verge.

Apple did not immediately respond to a request for comment.

An Apple logo hangs above the entrance to the Apple store on 5th Avenue in the Manhattan borough of New York City, U.S., December 5, 2016.

Many companies in the U.S. have been strengthening their COVID-19 rules, mandating vaccination and delaying back-to-office plans as the Omicron variant increases infections across the country.

This week, Facebook parent Meta Platforms (FB.O) mandated COVID-19 booster shots for all workers returning to offices. It also delayed U.S. office reopenings to March 28, from an earlier plan of Jan. 31. read more.

The iPad 2 with a Smart Cover is shown in use in the demonstration area after the iPad 2 launch during an Apple event in San Francisco, California March 2, 2011. Apple unveiled its next generation iPad at an event in San Francisco. Apple CEO Steve Jo

Alphabet Inc's Google (GOOGL.O) on Friday said it was temporarily mandating weekly COVID-19 tests for people entering its U.S. offices. read more

A report by The Information said Amazon.com Inc has offered its U.S. warehouse workers $40 to get a booster shot.