Washington DC - The Omicron variant, a new strain of Covid-19 triggering concern worldwide, could already be in the US.

Dr Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, said Saturday that while there is no indication the mutated virus has made its way over from South Africa, where it was initially detected earlier this week, citizens should take special care and avoid letting their guards down.

When asked whether he believed Omicron has already arrived in the US, Fauci said he "would not be surprised" if it has.

"We have not detected it yet, but when you have a virus that is showing this degree of transmissibility and you’re already having travel-related cases that they’ve noted in Israel and Belgium and other places, when you have a virus like this, it almost invariably is ultimately going to go essentially all over," Fauci said during an interview on the Today show.

South Africa’s health minister on Thursday announced the discovery of the variant, which appears to be spreading rapidly across parts of the country. Less than 24 hours later, the World Health Organization designated it as a "variant of concern," naming it Omicron during an emergency meeting held Friday.

The people in South Africa who have caught the Omicron strain of Covid-19 have not become seriously ill, Angelique Coetzee, who chairs the South African Medical Association, told the BBC.

However, research into the variant is still at a very early stage, she said, adding that only 24% of people are fully vaccinated in the country. The cases also involved younger people, who are more likely to develop milder forms of the illness.

Omicron has been found in multiple countries, including Israel and Belgium. And on Saturday, British Health Minister Sajid Javid confirmed two linked cases of the variant have been detected in Britain.

Other countries, including the US and the 27-nation European Union, have since moved to suspend all travel from South Africa.

The White House on Friday announced restrictions for travelers from eight African countries slated to go into effect on Monday.

Fauci said travel bans are simply a way of buying time given the threat of the virus.

"The issue of blocking travel from a given country is to just give us time to assess it better," he said. "That’s the reason for doing that, not any reason to panic, but we want to give us some time to really fill in the blanks of what we don’t know right now."