The top US infectious disease official, Dr Anthony Fauci, told President Joe Biden on Sunday it will take about two weeks to have definitive information on the new coronavirus variant Omicron that has sparked new travel restrictions and shaken financial markets.

Biden, returning to Washington following the Thanksgiving holiday weekend, was briefed in person by his coronavirus response team on Sunday afternoon as officials expect the new variant to reach the United States despite an impending ban on travellers from Southern Africa, where it was first detected.

Fauci said he believes existing vaccines are likely to provide "a degree of protection against severe cases of Covid"...