US President Joe Biden on Thursday is expected to announce that about two million civilian federal workers will need to be vaccinated against the coronavirus or face testing, social distancing, mask requirements and limits on travel, according to a source familiar with the matter.

Biden, who will deliver remarks on COVID-19 at the White House at 4 pm (2000 GMT) on Thursday, will not mandate vaccines for federal employees and those who decide against getting a vaccine will not be at risk of being fired, the source said.

The plan is similar to what some states and New York City have announced, the source added.

For example, New York Governor Andrew Cuomo said on Wednesday that state employees will be required to be vaccinated or get tested weekly.

On Tuesday, Biden said his administration was considering the requirement for federal employees.

Numerous US agencies on Wednesday mandated masks at federal buildings in COVID-19 hot spots in line with instructions issued by the White House Office of Management and Budget (OMB), according to an OMB email seen by Reuters.

The White House also said masks are required indoors in federal buildings for all employees and visitors, whether or not vaccinated, in those areas experiencing sharp increases in infections.

On Wednesday, the Centers for Disease Control and Prevention (CDC) said nearly 67% of US counties were at substantial or high transmission rates, up from 63.4% on Tuesday.

The federal government is racing to contain the pandemic in the hope of avoiding future nationwide shutdowns, as the virulent Delta variant of the coronavirus blazes through parts of the United States and immunisations lag.

Some organized labour groups such as the American Postal Workers Union (APWU) said it opposes a vaccine mandate for federal employees and expressed concern about Biden’s expected announcement.

“While the APWU leadership continues to encourage postal workers to voluntarily get vaccinated, it is not the role of the federal government to mandate vaccinations for the employees were present,” the group said in a statement.

Others such as AFL-CIO President Richard Trumka told C-SPAN that the union supports vaccine mandates.

“If you come back in and your are not vaccinated, everybody in that workplace is jeopardized,” Trumka said.