SEATTLE — Amid an uptick in coronavirus hospitalizations caused by the infectious delta variant, Amazon has pushed back its return-to-office date for tech and corporate workers until January 2022, according to internal messages seen by The Seattle Times.

Unlike crosstown rival Microsoft, Amazon will not mandate employees receive the COVID-19 vaccine before they return to the office. The Redmond, Wash.-based software company announced last week that it was pushing back its office reopening to October and will require employees to be fully vaccinated against the coronavirus to enter the company’s U.S. offices and other worksites.

Amazon continues to encourage employees to receive the vaccine, but will not require it, spokesperson Jose Negrete confirmed.

“As we continue to closely watch conditions related to COVID-19, we are adjusting our guidance for corporate employees in the U.S. and other countries where we had previously anticipated our employees would begin coming in regularly the week of Sept. 7,” Amazon human resources chief Beth Galetti wrote in an email to employees. “We are now extending this date to Jan. 3, 2022.”

The delay affects the roughly 60,000 people working in Amazon’s offices in Seattle and Bellevue, Wash., as well as tens of thousands more corporate Amazon employees worldwide.

Like many employers, Amazon has shifted its return-to-office plans several times, in response both to employee sentiment and changing coronavirus realities.

The company sparked employee backlash earlier this year when it announced it planned a “return to an office-centric culture” by autumn, which some workers interpreted as the expectation that they would be in the office full-time. Only 8% of Amazon corporate employees wanted to work full-time in the office, according to an internal 2020 sentiment survey seen by The Seattle Times.

The company relaxed its stance later this spring, saying that once offices reopen, employees could work remotely up to two days a week.

Amazon’s Thursday announcement pushes that reopening further off. “This has been such an unusual time for all of us,” an internal Amazon blog post announcing the delay read.

The vast majority of Amazon’s 1.2 million-person global workforce is still expected to show up on-site to pack boxes, sort merchandise and load and unload trucks at Amazon warehouses, where the company has rolled back coronavirus precautions in recent months.