Convention studies detail Omicron's early moves in US

The pre-Thanksgiving spread of the Omicron COVID-19 variant among fully vaccinated attendees of a New York City Anime convention was an early sign the variant was able to evade vaccines, according to a study today in Morbidity and Mortality Weekly Report (MMWR).But despite a high attack rate among close contacts, the convention itself was likely not a super-spreading event, according to another study published today in MMWR, and it had limited impact on the variant's introduction to the United States, researchers said.The convention, held at the Javits Center from Nov 19 through the 21, 2021, included 53,000 attendees from 52 US jurisdictions and 30 foreign countries, the authors said.

Masks were required during the convention, and attendees had to show proof of at least one dose of COVID-19 vaccine.High spread in close contactsThe Omicron variant was detected in patient A, an attendee from Minnesota who was fully vaccinated and boosted but developed symptoms of COVID-19 the day after attending the convention.On Dec 2, 2021, the Minnesota Department of Health identified patient A as he first case of community-acquired COVID-19 in the United States caused by the Omicron variant.

Twenty-nine close contacts from the convention were identified, and 23 were interviewed. The close contacts socialized at bars and restaurants without masks on, and performed karaoke together.All 23 close contacts were fully vaccinated, including 11 (48%) who had received a booster dose; all 23 sought testing, and 16 (70%) received a positive SARS-CoV-2 test result.

Subsequently 6 household members of the positive 16 cases also tested positive for the virus in the days following the convention.