(NewsNation Now) — The omicron variant of the coronavirus has been found in at least 15 U.S. states as of Saturday night but the Delta variant remains the majority of COVID-19 cases nationwide, U.S. Centers for Disease Control and Prevention Director Rochelle Walensky said on Sunday.

Omicron was designated as a variant of concern in November as scientists continue to study the risks posed by the new strain of the virus.

It’s not clear where the new variant first appeared, but scientists in South Africa alerted the World Health Organization, and it has now been seen in travelers arriving in several countries, including Australia, Israel, France, the Netherlands and Japan.

Adding to the confusion, the Netherlands announced on Nov. 30 that the omicron variant was already in the country when South Africa initially alerted WHO. The Netherlands’ RIVM health institute found omicron in samples dating from Nov. 19 and 23.

A person in California became the first in the U.S. to have an identified case of omicron variant on Dec. 1.

Massachusetts, Connecticut and Washington state announced their first cases Saturday, a day after New Jersey, Georgia, Pennsylvania and Maryland reported their first confirmed cases. Missouri also confirmed its first case Saturday.

Wisconsin officials announced late Saturday that they detected the first person with the omicron variant of the coronavirus in the state.

The Wisconsin Department of Health Services said the man had recently traveled to South Africa, where the variant has become prevalent.

New York announced three more cases of the omicron variant of the coronavirus Saturday, bringing the number of state cases linked to the new variant to eight.

“The omicron variant is here, and as anticipated we are seeing the beginning of community spread,” state Health Commissioner Mary Bassett said in a news release.

Here are the states that have detected cases of the omicron virus variant:

• California
• Connecticut
• Minnesota
• Colorado
• Georgia
• New York
• Hawaii
• New Jersey
• New York
• Maryland
• Massachusetts
• Missouri
• Nebraska
• Pennsylvania
• Utah
• Washington
• Wisconsin

The outbreak of omicron has made worldwide headlines and prompted political leaders to impose new COVID-19 restrictions.

Much remains unknown about omicron, including whether it is more contagious, as some health authorities suspect, whether it can thwart vaccines and whether it makes people as sick as the original strain.