After it was revealed that the first person known to have been infected with the Omicron variant in the United States attended a 53,000-person anime convention in Manhattan, concerns quickly mounted that the event had sown the seeds of a major outbreak of the coronavirus.
But a new study released Thursday by the Centers for Disease Control and Prevention suggested that a combination of proper air filtration, widespread vaccination and indoor masking actually helped prevent the November anime convention from becoming a superspreader event.
The proportion of participant tests that came back positive was comparable to the proportion of coronavirus tests that came back positive in New York City around the same time, the CDC said. In addition, the few positive samples that were genetically sequenced were largely from the Delta variant, not from Omicron.
And conventioners who became infected were more likely than those who tested negative to go to bars, nightclubs or karaoke clubs.
Still, the CDC said the spread of the virus at the convention could have been much worse had it been held after Omicron became dominant in the city, since the variant is so contagious and can spread among those vaccinated. At the anime convention, the CDC said in a separate report on Thursday that the only documented Omicron infections were in a single cluster of at least 16 positive cases.
The initial study was based largely on people signing up for tests after the event, introducing potential biases: Those people could have been more cautious than the average convention attendee, or more likely to report cautious behavior. Health officials had urged those present to be tested. The CDC could only search for cases among people on a ticket buyer’s registration list who did not count the full number of attendees.
The agency’s findings matched those of New York City contact tracing officials who said in early December they found no signs of widespread transmission at the anime convention.
In the aftermath of the event, which was held in the sprawling Javits Center, congress organizers came under fire when people reported that participants flouted masking rules and forced their way past checkpoints.
But among those in attendance tested, the CDC said, “evidence of widespread transmission at the event was not identified.”
The study was based on test results identified by health department monitoring systems for 4,560 attendees. Of those, 119 people – 2.6 percent – tested positive. Researchers also sent online surveys to attendees with questions about their test results, symptoms and activities during the convention.
The anime convention required attendees to have received at least one vaccine dose. The CDC said that of those attending that could be matched with testing and vaccination data in health department surveillance systems, 85 percent had completed their primary vaccination course, another 12 percent had received a booster dose, and 3 percent had been partially vaccinated.
The CDC study also credited the convention hall with being equipped with HEPA filters, which have been shown to efficiently remove the coronavirus particles from the air.