The White House’s Office of Management and Budget is telling federal agencies they should hold off on suspending or firing federal workers for not complying with the vaccine mandate until after the holidays, according to a memo obtained by ABC News.

This change, which has not yet been publicly announced, comes as President Joe Biden is putting pressure on private employers to embrace their own vaccine mandates.

Ninety-two percent of federal workers have already had at least one vaccine dose, according to the Office of Management and Budget. The federal workforce's compliance rate stands at 96.5%, meaning employees have had at least one vaccine dose or have a pending or approved exception or extension request.

-ABC News' Anne Flaherty

Dr. Ashish Jha, dean of Brown University's School of Public Health, told NBC's "Today" on Monday that he assumes omicron is already in the United States and predicts the new variant be identified in the next few days.

But Jha said he believes it's "extremely unlikely" that omicron would completely evade vaccines.

"I think that our vaccines will hold up -- the question is … is it a little bit less effective? A lot less effective? We will have that data -- both laboratory data and clinical data -- in the next week or two at the most," Jha said.

"I wouldn't make any major changes to plans" for the holidays yet, he continued. "I would just wait and make sure you're vaccinated and everybody around you is vaccinated."

"If you're fully vaccinated -- and especially if you're boosted -- you're going to have more protection against this variant," he said.

-ABC News' Cheyenne Haslett

Portuguese health authorities on Monday confirmed 13 cases of the omicron variant among professional soccer players.

The Ricardo Jorge National Health Institute said the players who tested positive are all members of the Lisbon-based Belenenses SAD soccer club and that one of them had recently traveled to southern Africa, where the omicron variant was first identified last week.

The institute is investigating whether this is one of the first reported instances of local transmission of the new coronavirus variant outside of southern Africa, where most of the cases have been recorded so far.

All 13 players have been placed in quarantine and those who have been in contact with them were ordered to isolate, regardless of their vaccination status or their exposure to possible contagion. The players and their close contacts will be regularly tested for COVID-19, the institute said.

-ABC News' Aicha El Hammar Castano

Moderna's chief medical officer, Dr. Paul Burton, said the omicron variant probably emerged around mid-October in southern Africa.

"How transmissible is it? We think it's probably quite transmissible. But how severe is the disease it causes? We don't know the answer to that question yet," Burton told ABC News' Amy Robach in an interview Monday on "Good Morning America."

"While we think that vaccine effectiveness may come down based on the mutations seen in this virus ... we should be able to get antibodies up" with the booster shot, Burton said.

"We'll know from tests in the next couple of weeks how effective the vaccines are against this variant," he added.