Six more US states have confirmed infections of the Omicron variant of COVID-19 but the Delta strain likely remains a greater threat as winter sets in and Americans gather for the holidays.
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 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.
Nebraska had six confirmed cases, the state's health department said. Only one of the six people was vaccinated and none are in hospital, the department added.
Maryland Governor Larry Hogan announced the first three cases of the Omicron variant in his state, adding that none of the three individuals were hospitalised. And in Pennsylvania, a Philadelphia man in his 30s tested positive for Omicron, city health officials said.
New Jersey Governor Phil Murphy said the state's first Omicron case had been found in a fully-vaccinated woman who had recently travelled to Georgia.
A surge in infections could further strain hospitals already grappling with high case loads and fatigued staff.
Omicron has been detected in about 40 countries and the CDC is investigating possible cases of the Omicron variant in other states.
Australian Associated Press