A handful of omicron COVID-19 variant cases in California have been connected to a wedding in Wisconsin from last month.

NBC Chicago reports that at least five people have tested positive for the omicron strain. Just a few days ago, the first U.S. case of omicron was discovered in California.

Another was identified in Minnesota.

The five people who have contracted the new variant are from a group of 12 individuals who are vaccinated and tested positive for coronavirus. One of the guests from the Nov. 27 Wisconsin wedding had “attended upon return from international travel,” according to the Alameda County Department of Public Health.

The group with the omicron strain have “mildly symptomatic cases.” The other seven people have also been subjected to genomic sequencing, which hasn’t yet concluded. Officials said that “most” of the 12 had gotten boosters, and ranged in age from 18 to 49. At this point, it’s unclear if omicron is more infectious than other strains, if it makes people more ill, and how effective the vaccine is against it.

A number of nations are looking to ban travel from South Africa since the variant was first detected in the country around Thanksgiving. The person in California who was identified as the first U.S. omicron case was traveling from South Africa to the U.S. on Nov. 22, and later tested positive for the variant on Nov. 29.

“The individual is self quarantining and all close contacts have been contacted and all close contacts, thus far, have tested negative,” Dr. Anthony Fauci said on Dec. 1. “We feel good that this patient not only had mild symptoms, but actually the symptoms appear to be improving.”