“We don’t know if we’ll see a lot of omicron, or we’ll see a lot of delta,” Ehresmann said in an interview. “But we’re likely to see a lot of covid” out of the convention, which drew 53,000 people and tightly packed crowds from Nov. 19 to 21.
The development is not sufficient, by itself, to determine where people were infected, who gave the virus to whom, or to develop a timeline of its spread, Ehresmann said. The man infected with omicron also spent time elsewhere in New York City. New York, Minnesota and other states, as well as the Centers for Disease Control and Prevention, are investigating the case and have begun tracing the Minnesota man’s contacts.
But the information casts the convention as a more likely location where the virus could have spread widely. Scientists have speculated the new variant may be significantly more transmissible than the delta variant, which has swept the country in recent months, but are still gathering data on a pathogen first identified last week.
“The conference seems like the most likely spot because of the extreme mixing of so, so many people,” Ehresmann said. “It was just a very large gathering that provided the opportunity for a lot of mixing for many people across the country.”
The unidentified man flew to New York on Nov. 18 and his symptoms began Nov. 22, which would indicate a short incubation period for the omicron variant if he picked it up in New York, Ehresmann said. The man had been vaccinated and received a booster shot in November, officials said.
The man’s symptoms were mild and resolved Nov. 24, health authorities have said. He lives with other people, one of whom tested positive on a rapid test and is being investigated further, they have said.
Organizers of the convention, Anime NYC, said in a statement that “many are making the assumption that the individual contracted the Omicron Variant sometime during their travel to New York City, in New York City, or when traveling home from New York City. No one knows when or how the Omicron Variant was contracted.”
A spokesman said the organization had not been informed of any additional infections.
The event’s organizers and attendees have described a heavily attended convention, with fans of the Japanese style of animation packed tightly in places inside and outside the vast Javits Center in the Hell’s Kitchen neighborhood of Manhattan. Video posted online shows a large crowd milling about in one location.
Attendees over age 12 were required to show proof of at least one vaccine shot, as directed by New York City rules for large indoor events, and to wear masks. Attendees said most people followed the mask guidelines, though some complained about the crowds and disorganization.
Lizzette Lewis, 42, a special-education and Zumba teacher from New York, said she was excited to get back to a convention after the hiatus, particularly in her hometown. Fully vaccinated and about to get her booster, Lewis said she felt confident going in.
“Was everyone following the mask mandate? Not quite, including myself,” Lewis said. “If nobody was around, I’d give myself a moment to breathe.”
Kassie Kelly, 30, who lives in Jersey City, said she saw about five people who weren’t wearing masks. And she and her fiance have tested negative.
“I don’t feel like anyone in particular is to blame,” for the emergence of the Minnesota case, she said. But she was also struck by her good luck.
“I feel like I should buy a lottery ticket,” Kelly said.
New York Mayor Bill de Blasio (D) issued a statement Thursday saying that “anyone who attended the Anime NYC conference, especially anyone experiencing symptoms, should get tested immediately and take additional precautions, including social distancing.”
City and state health authorities, New York’s Test and Trace Corps and the CDC are contacting convention attendees, the statement said.
De Blasio also said “we should assume there is community spread of the variant in our city.”
At a news briefing Thursday, New York Gov. Kathy Hochul (D) said contact tracing “will not be as complicated as it has been in the past. … We anticipate even if people do test positive the symptoms will be fairly minor.”
Jennifer Nuzzo, a senior scholar at the Johns Hopkins Center for Health Security, said in a case where a person contracted the virus while moving about a mass gathering, authorities will trace the people with whom he spent large amounts of time, such as friends and dinner companions. It’s not possible to trace short contacts at a convention, even if they could be determined, she said.
More important in an outbreak of a new variant, Nuzzo said, is investigating whether it behaves any differently from previous strains of the virus. Authorities will want to know whether the Minnesota man’s friends were vaccinated, how sick they became, how often they wore masks and whether there is anything new about their cases, she said.
“It’s less because you’re trying to interrupt transmission than you’re trying to understand how this virus is spreading,” she said.
Officials in Norway said at least 50 people have been infected with omicron, with the cases connected to a Christmas party at an Oslo restaurant.
The Wisconsin Department of Health Services said in a news release Friday that there was a covid-19 outbreak from a November wedding in Milwaukee County. Five of the 12 people — all California residents — who have tested positive were infected with the omicron variant, Wisconsin officials said. Genomic sequencing is not yet available for the other cases. The 12 people are between the ages of 18 and 49 and vaccinated, officials said, and are “mildly symptomatic.” No one has been hospitalized.
The potential for the spread of a coronavirus variant from a large, crowded event when the pathogen’s behavior was unknown is reminiscent of an episode in February 2020, when a Boston biotech conference resulted in wide and rapid transmission.
Biotech executives from around the world flew into Boston for the annual leadership meeting of the drug company Biogen. It became a superspreader event.
The Massachusetts Department of Health identified 97 coronavirus cases among meeting attendees and people who lived with them. Genetic testing showed that the same viral sub-strain infected 122 residents at two Boston homeless shelters in April.
According to a study of coronavirus genomes, the variant detected at the Biogen conference spread as far as Alaska, Senegal and Luxembourg and as of July 2020 was found in one-third of cases in Massachusetts and 3 percent of genomes studied in the United States.