First case of coronavirus omicron variant confirmed in Sonoma County

The person infected with the highly transmissible coronavirus mutation had recently received a vaccine booster and had traveled out of state.|

Sonoma County officials confirmed Friday that their public health lab detected the first local case of omicron, the highly transmissible coronavirus variant that has health officials worried about another spike in the stubborn pandemic.

“I’m not surprised. It was expected,” county Health Officer Dr. Sundari Mase said Friday morning. “Omicron cases have been happening in other counties in the Bay Area.”

The first confirmed example of omicron in the United States, detected Dec. 1, was in California. It has been identified in 39 states now.

As of Dec. 15, according to the California Department of Public Health, 49 confirmed cases of omicron had been reported to the state. Now there are at least 50, though most researchers assume the true scope of the variant’s reach far exceeds that number.

Mase declined to estimate the percentage of current coronavirus cases caused by omicron, citing the puny amount of hard data she has to analyze that.

The person known to be infected by omicron in Sonoma County was fully vaccinated, Mase said. They had recently received a booster, but were still within the two-week window of antibody production. The person also had recently traveled within the continental United States.

When a new variant emerges, epidemiologists and medical researchers typically seek to determine how it compares to other genetic variations on three measures: transmissibility, virulence and resistance to vaccines. Early studies paint omicron as more dangerous on two of the three variables.

The good news is that the newest variant of concern appears to bring less chance of severe illness. A study by Discovery Health, South Africa’s largest insurer, indicated that risk of hospital admissions among adults who contract the virus is about 29% lower for omicron than during the initial thrust of the pandemic in March 2020.

On the other hand, the same study revealed that the two-dose Pfizer-BioNTech vaccine provides just 33% additional protection from infection via omicron, much lower than the vaccine offers against other variants.

And a professor of health and environmental sciences at Kyoto University in Japan who uses mathematical modeling of infectious diseases estimated that omicron is 4.2 times more transmissible than the variant currently dominant in California, delta — which is itself several times more easily spread than the first detected permutation of the SARS-CoV-2 virus.

“That’s the big worry,” Mase said. “Because if it’s more transmissible, there will be more cases. Especially in indoor settings, and especially as we move into the holidays.”

Still, Mase cautioned against becoming overly alarmed at the local discovery of the omicron variant.

“It doesn’t change what people should be doing,” she said. “And that means get vaccinated, get your boosters, wear masks in indoor settings, socially distance in those indoor settings and try not to gather in a large group indoors. Those things have not changed.”

Vaccination is vital despite the possibility of “breakthrough” cases among vaccinated residents, Mase said, because it has proved effective in preventing severe outcomes like hospitalization. She said there also seems to be growing evidence that vaccination can help ward off omicron transmission outright.

Those were among the reasons Sonoma County joined 10 others in the Bay Area on Friday to officially urge all eligible residents to get fully vaccinated as soon as possible, including a booster shot. You are eligible for a booster if you are at least 16 years old and six months out from your second shot of Pfizer; at least 18, and six months out from your second shot of Moderna; or at least 18, and two months out from your first shot of Johnson & Johnson.

Currently, just 30% of eligible Sonoma County residents, and 57% of those over the age of 50, have received a booster.

Health officers like Mase have been concerned for weeks that holiday gatherings, combined with winter weather that drives people indoors, could fuel another surge. Those worries remain, but Mase emphasizes that current coronavirus transmission is a far cry from last winter’s deadly spread. Sonoma County’s current rate is 11.4 new cases per day per 100,000 people; last year at this time, the rate was in the 40s.

“Again, that’s all due to vaccination,” Mase said. “Even with the variants, we still have one-quarter of the case rate.”

She added that health officials recommend that anyone who travels outside California this winter get a COVID test three to five days after returning home.

Sonoma County Public Health acquired a diagnostic machine in July that allows it to do genetic sequencing on coronavirus tests. But the public lab does only a small portion of the county’s testing, meaning Mase’s department has no access to most samples.

“That’s the hard part,” she said. “These tests are being run in many different labs. Hospital labs, for example Kaiser, send specimens to their regional lab. Some go directly to the state. Some to private labs as well. And no one is analyzing (rapid) antigen tests.”

That array of testing facilities leads to lags in data collection, and probably means the state has no true idea of how many Californians have been infected by omicron.

You can reach Phil Barber at 707-521-5263 or On Twitter @Skinny_Post.

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