The World Health Organization (WHO) said on Wednesday it does not yet have enough data on the new Omicron variant of the coronavirus to say if it is more severe than the Delta variant.
"We do have some data suggesting that rates of hospitalization are lower," WHO's technical lead on COVID-19, Maria van Kerkhove, said in a briefing with media, according to the Reuters news agency.
She also cautioned against drawing conclusions from the early data because "we have not seen this variant circulate long enough in populations around the world, certainly in vulnerable populations".
Data on the new variant, first identified in southern Africa and Hong Kong in November, was still "messy" as countries reported its arrival and spread, said van Kerkhove.
"We have been asking people to be cautious, we have been asking countries to be cautious, and to really think, especially as these holidays are coming up," she added.
The Omicron strain has become the dominant version of the coronavirus in the US, accounting for 73% of new infections last week.
On Monday, the US recorded its first death from the Omicron variant, an unvaccinated Houston man in his 50s with underlying health conditions.
A day earlier, top US pandemic advisor Dr. Anthony Fauci warned of a “bleak winter” ahead as Omicron spurs a new wave of infections globally.
"One thing that's very clear... is (Omicron's) extraordinary capability of spreading," Fauci told NBC News. "It is just... raging through to the world."