WASHINGTON (REUTERS) - Preliminary evidence indicates that the Omicron variant of the coronavirus likely has a higher degree of transmissibility but is less severe, top US infectious disease expert Anthony Fauci said on Tuesday (Dec 7).

Although more data is needed, early cases of Omicron seem to require fewer hospitalisations and patients are less likely to need oxygen, Fauci told reporters at a White House briefing.

More data is expected next week, Fauci said, but it will take a few weeks to reach any definitive conclusions.

The United States is continuously reevaluating travel restrictions it imposed on some southern African countries when Omicron was first detected, but they will remain in place for a"reasonable period of time," White House Covid-19 response coordinator Jeff Zients said at the briefing.

Zients said the US administered 12.5 million vaccines in the last week, the highest number of vaccinations since May, around seven million of which were booster doses.