An anime convention held in New York City last month may inadvertently offer the US its first case study on the spread of the omicron coronavirus variant, according to the Centers for Disease Control and Prevention.

Fifty-three thousand anime fans from all 50 states, the District of Columbia, Puerto Rico, and 27 other countries traveled to New York City for the Anime NYC convention, which ran from November 19 and 21 in the city’s Javits Center. Organizers reported afterward that they were overwhelmed by the large attendance and struggled with packed rooms and crowding—conditions ideal for coronavirus transmission.

Last week, officials in Minnesota reported that a resident tested positive for the omicron variant after attending the convention. At the time, it was only the second omicron case detected in the US. But since then, officials have identified cases in at least 18 other US states, as well as over 50 countries worldwide.

The discovery of omicron at a large, tightly packed event with far-flung travelers is concerning. The variant is thought to be ultratransmissible. Preliminary reports from South Africa suggest omicron may spread more than twice as quickly as the already hypertransmissible delta variant. In such a crowded convention, omicron could swiftly spread among attendees and be carried back to home states and countries for further spread.

Spotting spread

Omicron is, in all likelihood, rapidly escalating in the US. Despite this, health officials have been relatively slow in detecting the variant. Genomic surveillance of variants is patchy and limited across states, though it has improved since the pandemic began. Another factor working against the country is the still extremely high levels of delta transmission. Any relatively small rise in omicron cases could easily be washed out by the massive delta wave.

But the anime convention provides a specific source of transmission that health investigators can use to get a clearer look at how omicron is spreading. The CDC has teamed up with the Minnesota and New York City health departments to retrace omicron’s steps through the massive event.

In a press briefing Tuesday, CDC director Rochelle Walensky said that the CDC has reached out to all states, territories, and countries with residents who attended the convention and hopes to reach all of the reported 53,000 attendees. So far, health officials have contacted more than 35,000 of them.

“Data from this investigation will likely provide some of the earliest looks in this country on the transmissibility of the variant,” Walensky said during the briefing.

Contact tracers will likely have their work cut out for them. On December 4, Connecticut announced that it had detected its first omicron case in a man in his 60s. The man had a family member who had tested positive for COVID-19 days earlier after returning from the anime convention in New York.

In a New York Times article published December 5, the Minnesota man first found to have an omicron infection after the convention said that roughly half of the 30 vaccinated people he recalls socializing with have tested positive. He told the paper that he had spent his time in New York attending discussion panels at the convention, chatting with strangers, and singing karaoke.

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