Jan 15 (Reuters) - 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. 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 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.