Governor Kathy Hochul of New York confirmed five cases of the coronavirus Omicron variant on Thursday, raising the total number of US detections to eight.

"New York State has confirmed five cases of the omicron variant," Hochul wrote on Twitter, reassuring residents of the country's fourth-largest state that the detections were not unexpected.

"Let me be clear: This is not an alarming situation. We anticipated this variant's arrival and have the instruments necessary to halt its spread," she explained. "Receive your vaccination. Acquire your booster. Put on your mask."

It was unclear immediately whether the new instances occurred in or around New York City — the country's most populous metropolitan area — or whether they were detected in individuals who had recently returned from international travel.

Eight cases have been confirmed in the United States, with at least one involving a person with no recent international travel history, indicating that the strain is already circulating within the country.

Hochul's findings came on the heels of President Joe Biden's declaration that he is increasing his administration's fight against Covid-19 as winter approaches.

The latest measures include requiring all international tourists to undergo testing within one day of arrival and extending the mask mandate on public transit through mid-March.