The Omicron variant has spread from coast to coast in the U.S., with at least five states confirming cases of the COVID strain.

The first case was detected in San Francisco on Wednesday. The person had traveled to South Africa via London in late November and was experiencing mild symptoms.

“We knew that it was only a matter of time until the Omicron variant was detected in our city, and the work that we have done to this point has prepared us to handle this variant,” San Francisco Mayor London N. Breed said in a statement.

Since that initial case, at least five people have been infected with the variant in New York, in addition to cases in Minnesota, Colorado, Hawaii and another case in Los Angeles County, bringing the total case count to 10 by Thursday.

The case in Minnesota involved a man who had attended Anime NYC 2021 in Manhattan from Nov. 19 to Nov. 20, testing positive for the virus on Nov. 22, according to the Minnesota Department of Health.

The man was fully vaccinated and has since recovered.

Minnesota Gov. Tim Walz said in a statement. “This news is concerning, but it is not a surprise. We know that this virus is highly infectious and moves quickly throughout the world. Minnesotans know what to do to keep each other safe now — get the vaccine, get tested, wear a mask indoors and get a booster.”

The case in Colorado was a woman who had traveled to southern Africa recently, Colorado health officials said. The woman was fully vaccinated but had not received her booster shot.

She has mild symptoms and is isolating.

The five cases in New York were found in Suffolk County and four in the New York City metropolitan area.

The Suffolk County resident had traveled to South Africa and was asymptomatic. It is unclear if the other four cases are connected to the Anime NYC 2021 event.

"As I've said since we first became aware of the emergence of the Omicron variant and said earlier today, it was only a matter of time before it was detected here in New York state,” Gov. Kathy Hochul said in a statement.

The case in Hawaii involved a person who had no recent travel history. The individual is located on the island of Oahu and has moderate symptoms. The person is not vaccinated, the Hawaii Department of Health said.

A case was reported in Los Angeles County in a person who had traveled to South Africa on Nov. 22.

“The individual, who is a fully vaccinated adult and a Los Angeles County resident, is self-isolating, and their symptoms are improving without medical care,” Los Angeles County health officials said in a statement. “A small number of close contacts in Los Angeles have been identified and, to date, all have tested negative and have no symptoms.”

The Omicron variant was first detected in South Africa, where health officials warned the world about the new strain last week.

Very little is known about the new variant as experts scramble to determine if the Omicron strain is more transmissible and deadly.

The Omicron variant has been detected in at least 23 countries.

The study followed nearly 1,300 people hospitalised for Covid between January and May 2020 in the central Chinese city of Wuhan, the first city affected by the pandemic
Representational image of a man in hospital after contracting COVID-19. AFP / Yasuyoshi CHIBA