Second U.S. case of Omicron variant indicates domestic transmission

Health officials on Thursday reported the country’s second Covid-19 infection from the Omicron variant in a Minnesota resident who notably did not travel internationally recently, unlike the first case.

The case in Minnesota is an adult male who had been vaccinated and, in early November, received a booster shot. He lives in Hennepin County, which includes Minneapolis, state health officials said. He developed mild symptoms on Nov. 22, was tested on Nov. 24, and no longer has symptoms. 

The man had been in New York City in the days leading up to feeling sick and attended the Anime NYC 2021 convention at the Javits Center from Nov. 19 to Nov. 21. Minnesota health officials are collaborating with New York City authorities and the Centers for Disease Control and Prevention on their case investigation.

“The primary goal of vaccination all along has been to prevent severe disease so it’s very encouraging that vaccines are still successful in that regard,” Jan Malcolm, Minnesota’s health commissioner, said at a briefing.

State officials said one close contact of the man has tested positive on a rapid test, but they haven’t yet confirmed the case or sequenced the virus from that possible infection.

The new case demonstrates that there is at least some local transmission of the Omicron variant and that it had arrived in the U.S. before the Biden administration imposed travel restrictions on Botswana and South Africa — where early cases of the variant were detected — and six neighboring countries. Some two dozen countries have now reported cases. 

The case also indicates that the variant was in the United States even before the global research community knew about the threat the variant potentially posed. It will likely add fuel to the calls for the Biden administration to lift its travel ban on the southern African nations, which is seen by scientists as penalizing the region where researchers have simultaneously been praised for their speedy detection work and for sharing their findings quickly and transparently. 

Experts have said it was likely Omicron was spreading in the United States at some level, and it was just a matter of time before genomic sequencing of infections started detecting it. 

According to the anime convention’s website, attendees had to show they had at least one dose of a Covid-19 vaccine, but could attend immediately after getting a shot. It takes days if not more than a week for the vaccine-elicited protection to kick in.

Some 46,000 people attended the convention in 2019, according to its site.

The first U.S. Omicron infection was detected by researchers in San Francisco and announced Wednesday. The person, whose age and sex were not provided, had recently returned from a trip to South Africa. The person was vaccinated and had not had a booster shot, and reported only mild symptoms.

Later Thursday, health officials in Colorado also reported an Omicron infection, in an adult woman who had recently traveled to southern Africa. An Arapahoe County resident, she was vaccinated, had not received a booster, and had minor symptoms. Close contacts so far have tested negative.

Experts urge people showing symptoms of Covid-19 to get tested and to report relevant travel history to authorities. 

Scientists are scrambling to better understand the Omicron variant. They initially raised alarms about because its number and combination of mutations suggested it may be able to escape some amount of immune protection, and because limited epidemiological evidence in South Africa suggests it can compete with the highly transmissible Delta variant. But experts stress they still need to learn much more about Omicron’s transmissibility, severity, and immune evasion before they can assess how much of a threat it is to the world, and to vaccine protection. 

Megan Molteni contributed reporting.