New York officials have confirmed five cases of the omicron Covid-19 variant in the New York City metropolitan area, Gov. Kathy Hochul announced late Thursday, hours after cases were detected in Minnesota and Colorado.

One case was discovered in Suffolk County on Long Island and four in three of the boroughs that make up New York City: two in Queens, one in Brooklyn and one in Manhattan, she said at a press briefing. Minnesota health authorities confirmed the second U.S. case of the omicron Covid variant earlier Thursday, in a resident who recently returned from New York City.

New York City Health Commissioner David Chokshi said the cases indicate there was community spread, adding that the state is sequencing about 15% of all Covid tests, allowing them to “pick up these trends over time.”

“This is not just people who are traveling to Southern Africa or to other parts of the world where omicron has already been identified,” he said.

Hochul assured residents that the discovery of omicron cases in New York doesn’t mean she will call for the same kind of widespread lockdowns at the beginning of the pandemic that shuttered businesses and put millions of New Yorkers out of work.

“We are in a far better place, that people are informed. There’s not a panic,” she said Thursday night. “It is still a public health crisis, but does not have to be a crisis that leads to shutdown.”

The first confirmed U.S. case of the heavily mutated strain was detected in California in a resident who had just returned to San Francisco from South Africa, which first reported the strain to the World Health Organization about a week ago. The Colorado case was also confirmed in a traveler who had just returned from Southern Africa.

The California, Minnesota and Colorado cases were all diagnosed in fully vaccinated people who had mild cases. Hochul said the Suffolk County case is in a 67-year-old woman who had at least one vaccine shot and just returned from South Africa with mild symptoms. The case in New York City is in another suspected traveler, she said. Officials didn’t yet have any details on the cases in Queens and Brooklyn, but she said they would share them as soon as they were available.

Minutes after New York officials concluded their press conference, health officials in Hawaii confirmed via Twitter their first omicron case on the island of Oahu.

Health officials in the U.S. and around the world are concerned that omicron is more transmissible and may evade the protection provided by currently available vaccines to some degree. The variant has some 50 mutations, more than 30 of which are on the spike protein that the virus uses to attach to human cells.

“The molecular profile of the kinds of mutations that you see [in omicron] would suggest that it might be more transmissible and that it might elude some of the protection of vaccines,” White House chief medical advisor Dr. Anthony Fauci told reporters on Wednesday. “But we don’t know that now.”

The Biden administration on Thursday laid out a plan to combat omicron and a possible winter surge of the predominant delta variant of the virus. The White house is requiring all in-bound international travelers to test for Covid within 24 hours of their departure. The administration is extending mask requirements on domestic flights and public transit through March 18. It is also expanding access to free at-home Covid tests.

The WHO on Wednesday said omicron has been confirmed in at least 23 countries worldwide. The variant was first identified in Botswana last month and brought to the attention of the WHO by public health officials in South Africa.

Maria Van Kerkhove, the WHO’s technical lead, said on Wednesday that hospitalizations are rising in South Africa, but more data is needed before drawing conclusions about whether omicron causes more severe disease.

The patient in California who tested positive for omicron was fully vaccinated, has mild symptoms and is improving, Gov. Gavin Newsom said on Wednesday. The person, who is between 18 and 49 years old, had not received a booster dose because they were not six months out from their original vaccination course.

Dr. Mark Ghaly, California’s Health and Human Services secretary, said the fact that the patient has mild symptoms and is improving underscores the importance of vaccines.

The CEOs of Pfizer and Moderna say it will take about two weeks to gather enough data to determine what impact omicron’s mutations have on the effectiveness of the current vaccines. They have said it would take until early 2022 to develop a shot that specifically targets the variant. However, Moderna CEO Stephane Bancel said the company can roll out a higher dosage booster shot much quicker.