"Confirmed cases as of yesterday were 205 in 18 countries, and just this morning, that’s gone up to 226 in 20 countries, and I think you’re going to expect to see those numbers change rapidly. Importantly, it has not yet been detected in the United States," Fauci said during a press briefing.

Concern over the new Omicron variant has prompted countries around the world, including the US, to restrict travel from southern African nations where the strain first appeared.

The virus variant has a "very different" mutation profile from other variants of concern such as Delta, although it is difficult to determine whether it is more transmissible, Fauci noted.