Amazon has told warehouse employees in the US to once again wear masks at work, as the Delta variant is spreading fast in the country.

The company said masks are now mandatory regardless of vaccination status.

“In response to the concerning spread of new Covid-19 variants in the US and guidance from public health authorities and our own medical experts, we are requiring face coverings indoors regardless of vaccination status,” Amazon said in a statement given to The Verge on Friday.

“We are monitoring the situation closely and will continue to follow local government guidance and work closely with leading medical healthcare professionals, gathering their advice and recommendations as we go forward to ensure our buildings are optimised for the safety of our teams”.

Non-warehouse employees don’t have to follow Amazon’s policy change on wearing masks at work.

Amazon has also announced to delay its return-to-office timeline by January 2022.

“As we continue to closely watch local conditions related to Covid-19, we are adjusting our guidance for corporate employees in the US and other countries where we had previously anticipated that employees would begin coming in regularly the week of September 7. We are now extending this date to January 3, 2022,” the company said in an update.

“Our return-to-office timeline will vary globally in accordance with local conditions,” the company added.

The number of people in the hospital in the US has more than tripled over the past month, from an average of roughly 12,000 to almost 43,000, according to the Centers for Disease Control and Prevention (CDC).

The variant has sent cases surging to 94,000 a day on average.

Microsoft has also pushed its full office reopening date from September to “no earlier than October 4, 2021”, as the Covid cases rise in the US.

Facebook said last week that it would require its US employees to be vaccinated against Covid-19 when they return to the office.

Twitter has shut offices in the US, and Google and Alphabet CEO Sundar Pichai said the company will require employees to be vaccinated before returning to the office in the later part of the year.