A person in California who had been vaccinated against COVID-19 became the first in the U.S. to have an identified case of the omicron variant, the White House announced Wednesday as scientists continue to study the risks posed by the new virus strain.

Dr. Anthony Fauci told reporters that the person was a traveler who returned from South Africa on Nov. 22 and tested positive on Nov. 29. Fauci said the person was vaccinated but had not received a booster shot and was experiencing “mild symptoms.”

The Centers for Disease Control and Prevention is taking steps to tighten U.S. testing rules for travelers from overseas, including requiring a test for all travelers within a day of boarding a flight to the U.S. regardless of vaccination status. It was also considering mandating post-arrival testing.

Officials said those measures would only “buy time” for the country to learn more about the new variant and to take appropriate precautions, but that given its transmissibility its arrival in the U.S. was inevitable.

Much remains unknown about the new variant, including whether it is more contagious than previous strains, whether it makes people more seriously ill, and whether it can thwart the vaccine. Fauci, the top U.S. infectious disease expert, said more would be known about the omicron strain in two to four weeks as scientists grow and test lab samples of the virus.

An armed man who was shot by three police officers after he allegedly threatened them in Forest Lake over the weekend has died, authorities said Wednesday.

Bradley George Erickson, 47, of Forest Lake, was shot Sunday after police responded to a report that a man was in a residence with a gun and the man had a protective order against him.

Erickson left the scene in a vehicle that was eventually disabled by police, who fired on Erickson following an altercation, authorities said. Erickson died Wednesday at Hennepin County Medical Center, authorities said.

Cam Kauffman can be reached at kauf8536@stthomas.edu.