WASHINGTON, Dec. 3 (REUTERS) -- Six more US states confirmed infections of the Omicron variant of COVID-19 on Friday (Dec 3) but the Delta strain likely remains a greater threat as winter sets in and Americans gather for the holidays, experts said.

New Jersey, Maryland, Missouri, Nebraska, Pennsylvania and Utah each reported their first cases of the Omicron variant on Friday. Missouri was awaiting CDC confirmation of a case involving a St Louis resident who had recently travelled within the United States.

Scientists are still investigating the impact of the highly contagious Omicron variant, which was first detected in South Africa. Early evidence has suggested it may cause milder illness than its predecessors, including Delta.

The outbreak of Omicron has made worldwide headlines and prompted political leaders to impose new COVID-19 restrictions. But the predominant US strain remains Delta, Rochelle Walensky, director of the US Centers for Disease Control and Prevention (CDC), told a briefing at the White House.

Omicron has been detected in about 40 countries, including the United States, where it has also been found in California, Colorado, Hawaii, Minnesota, and New York.

The CDC said it was investigating possible cases of the Omicron variant in other US states.