CNN Business  — 

Amazon on Thursday pushed back its office return date until early next year amid a surge in Covid-19 cases from the Delta variant, making it one of the most significant delays yet in the tech industry.

The online retail giant’s corporate workers in multiple countries, including the United States, were originally slated to start coming back to the office by September 7, but that date has now been moved to January 3, 2022, Amazon (AMZN) told CNN Business.

When they do return, employees will be required to wear masks inside the office unless they have shown proof that they are vaccinated, the company added.

The change for corporate workers comes after Amazon dialed back some pandemic safety precautions for its warehouse workers. Amazon recently said it would stop offering on-site Covid-19 testing by the end of July, citing the wide availability of testing and vaccines. In late May, Amazon informed workers that it would lift its mask mandate for fully vaccinated warehouse employees, a change that came after guidance from the US Centers for Disease Control and Prevention that said fully vaccinated people can go without masks in most circumstances as long as it is in line with workplace and local business policies.

Many of the tech industry’s biggest companies, who were among the first to shut down their offices at the start of the pandemic last year, had set September as the target to reopen. Now these companies are delaying those plans as concerns about the Delta variant increase — and in some cases they’re requiring vaccinations for employees who are returning.

Google (GOOGL) last week announced it would push its office return date from September 1 to October 18, while ride-hailing company Uber (UBER) said it won’t reopen offices until October 25. Apple (AAPL) CEO Tim Cook also confirmed in an interview with CNBC that the company will delay its planned September reopening by at least a month.

Microsoft (MSFT), which like Amazon is headquartered near Seattle, has also postponed its full reopening and said earlier this week that it won’t allow all workers back before October 4.

At least one tech company — Lyft (LYFT) — is going even further than Amazon. The company’s CEO, Logan Green, told employees earlier this month that most of its US offices will now reopen on Feb 2, 2022.

CNN Business’ Sara Ashley O’Brien contributed to this report.