More than 20 people in the U.S. have tested positive for omicron. Here's what we know about the cases so far

More than 20 people in at least 12 U.S. states have tested positive for the omicron variant of the virus that causes Covid-19. The patients range in age, vaccination status and travel history, but none of them have developed severe disease so far.

While some patients had recently traveled in southern Africa, where the variant was first detected, others had no travel history, indicating that community transmission is underway in the U.S.

“We absolutely have community spread in this country,” Dr. Anthony Fauci told Bloomberg Television on Friday. “We don’t know how many of them, but there’s no doubt there’s community spread.”

Scientists and public health officials are still collecting data on whether omicron is more transmissible, better evades immune protection from vaccines, and/or causes more severe disease than other variants.

Those who have tested positive in the U.S. have all shown mild to moderate symptoms and none of the patients have been hospitalized so far, according to the most current information from state public health departments. However, mild cases of Covid can progress to more severe disease over time.

Many of the people who have tested positive in the U.S. were fully vaccinated. At least two of the patients who were immunized had not received booster shots yet, but another person had received their additional dose. And in at least one case, a person who had previously recovered from Covid tested positive for omicron.

While the handful of cases in the U.S. don’t provide any definitive answers about omicron, the World Health Organization said Friday that early data suggests the virus is more contagious. And South African scientists published a study, which has not yet been peer reviewed, that found omicron carries a higher risk of reinfecting people who previously caught Covid than past variants.

Although some of the people who tested positive for omicron were fully vaccinated, the fact that they have developed mild symptoms suggests that the shots are still providing protection against severe disease from the variant, U.S. health officials said. Fauci said Friday during a White House Covid briefing that lab studies indicate booster shots increase antibody protection against a range of variants.

“There’s every reason to believe that if you get vaccinated and boosted that you would have at least some degree of cross-protection,” Fauci said, “very likely against severe disease, even against the omicron variant.”

California confirmed the first U.S. case of omicron Wednesday in a person who recently returned from South Africa to the San Francisco area. The person was between 18 and 49 years of age, fully vaccinated and was not eligible for their booster shot yet, according to Gov. Gavin Newsom. The person showed mild symptoms and is expected to make a full recovery, Newsom said Wednesday.

“The evidence that an individual with omicron identified by sequencing actually has mild symptoms, is improving, I think is a testimony to the importance of the vaccinations,” said Dr. Mark Ghaly, California’s Health and Human Services secretary.

California confirmed a second omicron case Thursday in the Los Angeles area. That adult was also fully vaccinated and had recently returned from South Africa via London, according to the city health department. The person’s symptoms are improving without medical care, officials said.

“This infection is most likely travel-related,” the Los Angeles County public health department said. The department, citing privacy concerns, would not disclose the person’s age or booster status when asked by CNBC on Friday.

On Thursday morning, Colorado confirmed a case of omicron in a fully vaccinated adult woman who had not received a booster shot. The woman, like the first case in California, had a recent travel history to southern Africa, where the variant was first detected. She is experiencing minor symptoms and is recovering at home, according to Colorado’s health department.

Gov. Jared Polis told residents during a press conference Thursday that health officials believe community spread is low in Colorado at the moment. Health officials have not yet detected omicron through wastewater analysis, and they have not detected a second case through genetic sequencing yet.

“So if it was prevalent, we would know — it doesn’t mean it’s nonexistent,” Polis said.

Hawaii confirmed a case in Oahu on Thursday in a person who was previously infected with Covid, was never vaccinated and had no travel history, according to the state health department. The person is showing moderate symptoms, it said.

“This is a case of community spread,” the department said in a press release.

Maryland on Friday confirmed three people from the Baltimore metro area tested positive for omicron. Two of the people are from the same household, a vaccinated person who had recently traveled to South Africa and a close contact of that person who was unvaccinated. The third case was in a vaccinated person who had no known recent travel history, according to state officials.

“None of the three individuals are hospitalized,” Gov. Larry Hogan said in a press release.

The Massachusetts Department of Public Health announced the state’s first omicron coronavirus case on Saturday.

The infected person is a female in her 20s who traveled out of the state. Officials said she is fully vaccinated, experienced mild disease and did not require hospitalization.

In Minnesota on Thursday, public health officials confirmed an omicron case in an adult male who was fully vaccinated and had recently returned from an anime convention at the Javits Center in New York City. His symptoms were mild and have since resolved, according to the state health department.

The Minnesota resident had received a booster shot prior to attending the convention in New York, Minnesota public health spokesman Doug Schultz told CNBC on Friday.

A St. Louis resident with recent domestic travel history is presumed positive for omicron, the Missouri state health department said Friday. The sample was sequenced by a commercial lab and is awaiting confirmation by the Centers for Disease Control and Prevention.

The Missouri state health department did not provide information on the individual’s age, vaccination history or symptoms. Spokeswoman Lisa Cox told CNBC Saturday the state has no further information at this time.

Nebraska confirmed six omicron cases Friday, in a transmission chain that appears to have started with a person who recently traveled to Nigeria. The other five people were likely exposed through household contact with the person who had traveled to Africa, according to the state health department. Only one of the six people was vaccinated, but none of them have required hospitalization.

The New Jersey Department of Health has confirmed a case of omicron in a traveler from Georgia who was recently in South Africa. The adult woman, who is fully vaccinated, experienced moderate symptoms and is now recovering after receiving care in an emergency department in northern New Jersey, according to state health officials.

New York has identified eight cases total of the omicron variant.

A total of seven New York City residents and one from Suffolk County are confirmed to have the virus, as of Saturday morning.

New York City Health Commissioner Dave Chokshi told the public Thursday that the cases indicate there is community spread in the state.

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

A man in his 30s from northwest Philadelphia has tested positive for omicron, city officials confirmed on Friday. Philadelphia’s health department said it is working to get more information on the case.

Utah confirmed its first case of the omicron variant, public health officials confirmed Friday.

Officials said the individual who tested positive was an older adult who recently returned home to Utah after traveling to South Africa.

The person is fully vaccinated and showed only mild symptoms. They received monoclonal antibody treatment.

—CNBC’s Jessica Bursztynsky contributed to this report.