A holiday party in Marin County ten days ago where all attendees were vaccinated led to an outbreak of at least 28 cases of COVID, and health officials believe the Omicron variant was to blame.

"When we decided to have the party, we consulted the Centers for Disease Control website," says restaurant owner Mike Koeppel, speaking to the Marin Independent Journal. "We listened to a speech made by Dr. Fauci, and at the time he was saying, if you’re vaccinated there is no reason why you can’t have holiday parties."

The December 11 party at Farm House Local was, ostensibly, a responsibly thrown affair, where all guests were required to be vaccinated, many were boosted, and the hosts encouraged everyone to administer at-home tests the day of the party to make sure they were COVID-negative. Windows and doors were kept open during the party to improve airflow. The event was hosted by Mike and Eliza Koeppel, who are in their 50s and live in Larkspur, and there were about 60 guests who were around the same age or in their 40s.

Now, around half of the guests in attendance have been infected with COVID, and the outbreak began with news of one guest being symptomatic and testing positive on December 13. So far, no one has become severely ill or required hospitalization, which points to the effectiveness of the vaccines at preventing severe infection.

Mike Koeppel says that he tested positive on December 16, and he tells the Marin IJ, "I’ve had very minor symptoms. I’ve been one of the lucky ones."

"We feel terrible about what has happened," said Eliza Koeppel. "It’s just the worst nightmare."

County Health Officer Dr. Matt Willis says that Omicron was the likely culprit in this outbreak, due to the sheer number of those infected.

"Right now we know about half of the attendees of this event were infected," Willis tells the Marin IJ. "An attack rate of 50% is consistent with a very contagious virus. Delta has been highly contagious, but it hasn’t led to an attack rate of 50%."

Willis gave a countywide update Monday discussing how Omicron was likely to surge in the county in the coming days and weeks, and encouraging everyone whose original vaccinations were six or more months ago to go get a booster dose. Additionally, Willis says that the county will soon begin distributing 50,000 free at-home COVID tests to low-income families — and he's encouraging anyone attending an event to test themselves the day of the event.

Marin County has, during much of the pandemic, been the most thorough in its contact-tracing and in its public communications about outbreaks as they're detected. A classroom outbreak in May involving an unvaccinated teacher in Novato led to health officials drafting a paper about the incident that was then widely shared by the Centers for Disease Control.

A recent school outbreak in the county was found to have been caused by two infected children whose parents did not keep them out of school after one of them tested positive. Those parents are now facing possible criminal charges.

Previously: Marin County Parents Who Sent COVID-Positive Kid to School Could Face Criminal Charges

Photo: Andrew Kneckel