Big tech companies are making it mandatory for employees in the United States to get Covid-19 vaccinations before entering campuses, as the highly infectious Delta variant of the virus drives a resurgence in cases across regions.

Alphabet Inc’s Google and Facebook Inc said on Wednesday (July 28) all US  employees must get vaccinated to step into offices. Google is also planning to expand its vaccination drive to other regions in the coming months.

According to a Deadline report, streaming giant Netflix Inc has also implemented a policy mandating vaccinations for the cast and crew on all its US productions.

Alphabet Inc's Google also postponed its date for bringing employees back to its offices by a month to Oct 18, Chief Executive Officer Sundar Pichai wrote on Wednesday.

Employees who come back will be required to show proof of vaccination, Mr Pichai said in a note to employees that were posted on a Google website.

Facebook Inc also told employees it will require them to be vaccinated for Covid-19 in order to return to the company's US offices.

"As our offices reopen, we will be requiring anyone coming to work at any of our US campuses to be vaccinated," a Facebook spokeswoman said in a statement.

The company, which told employees of the policy on Wednesday, said it will have a process in place for those who cannot get vaccinated for medical reasons. "We will be evaluating our approach in other regions as the situation evolves," the spokeswoman added.

Facebook expects about 50 percent office capacity in the US by early September, with a full return by October. Employees can apply to work remotely permanently, and Chief Executive Officer Mark Zuckerberg has said he anticipates that as much as half of Facebook's employees will work remotely in the next decade.

Many tech companies including Microsoft Corp and Uber have said they expect employees to return to the office, months after pandemic-induced lockdowns forced them to shift to working from home. 

Meanwhile, Apple Inc plans to restore a mask requirement at most of its US retail stores on Thursday (July 29) for both customers and staff, even those who are vaccinated.

Apple already started requiring masks for employees at select stores earlier this month, and it pushed back a return-to-office deadline for corporate employees. It also began requiring masks for customers in a few counties based on local guidelines.

Now, Apple will again require masks for shoppers and employees at more than half of its about 270 US stores. The decision was spurred by rising cases, new local mandates, and US Centre for Disease Control and Prevention guidelines.

"After carefully reviewing the latest CDC recommendations, and analyzing the health and safety data for your local area, we are updating our guidance on face masks for your store," Apple told staff.

"Starting July 29, face masks will be required in store for customers and team members - even if they're vaccinated."

The company added it is making the change "out of an abundance of caution."

It also urged retail staff to get vaccinated but is not requiring it at this time.

"Apple encourages everyone who is eligible to receive a Covid-19 vaccine, to take it," the company wrote to retail employees. "Please talk to your doctor and decide what's right for you."

Apple has also informed corporate staff that they must wear masks inside of Apple office buildings, but not when they're outside. An Apple spokesman declined to comment.

In June, before cases began to climb again, the Cupertino, California-based company dropped its mask mandate at its US retail stores. Apple has also launched a new hybrid program for retail employees to let some staff work at either their retail location or from home - where they can handle online sales - depending on consumer demand.