(Reuters) -Facebook Inc has pushed back its office return date for all U.S. and some international employees until January 2022 due to concerns over the highly infectious Delta variant, the company said on Thursday.

The move comes days after Facebook said its U.S. employees must get vaccinated to step into offices.

Other tech giants including Alphabet Inc’s Google and Uber Technologies Inc have also said all their U.S. employees have to be vaccinated before returning to the office.

The resurgence of COVID-19 cases in the United States due to the Delta variant and the new guidance from the U.S. Centers for Disease Control and Prevention (CDC) that requires fully vaccinated individuals to wear masks have led companies to change their plans on return to office, vaccinations and masking.

AT&T Inc will require management employees to be vaccinated before entering a work location and plans to begin talks with its union partners to jointly align on a path forward for union-represented employees, a company spokesperson said on Thursday.

AT&T will implement the CDC’s guidance on face coverings for its employees, regardless of vaccination status, who come in to work locations in areas with high or substantial transmission of COVID-19.

Helicopter-taxi firm Blade Air Mobility, which ferries people to luxury destinations such as The Hamptons, on Thursday mandated that starting next month its passengers be inoculated against COVID-19.

On Wednesday, McDonald’s Corp said it would require its U.S.-based office workers to be vaccinated against the coronavirus and will delay a return of employees to its offices until at least October.

(Reporting by Tiyashi Datta and Ankur Banerjee in Bengaluru; Editing by Maju Samuel and Shailesh Kuber)