Governor Gavin Newsom places the swab in the holder after a self-administered rapid COVID-19 test at Native American Health Center in Oakland, Calif., on Dec. 22, 2021. (Harika Maddala/ Bay City News)

Napa County’s rate of new COVID-19 cases is now the highest it has been since the pandemic began, the county’s top health official said Tuesday.

The county has confirmed as many as 866 cases in a seven-day period since the omicron variant arrived in Napa, Public Health Officer Dr. Karen Relucio told the county Board of Supervisors Tuesday morning.

That figure outpaces the county’s previous one-week peak of 788 cases during last winter’s surge. The county has also confirmed as many as 337 cases in one day, more than double the previous peak of 143 set roughly one year ago.

Napa County is currently confirming roughly 60 cases per day per 100,000 residents, according to Relucio.

“The omicron variant has really taken hold across California,” she said, noting that some studies of the variant have shown it to multiply at 70 times the pace of the delta variant.

Relucio added that initial studies of omicron have found it to be nearly as infectious as measles.

The omicron variant now comprises nearly 60 percent of the county’s cases, with the remaining cases being the delta variant, which has made up the vast majority of Napa County’s cases since June.

Even with omicron’s high transmissibility, Relucio argued that residents should make use of the existing tools available to prevent infections and reduce their severity, including vaccination and the use of high-quality masks such as N95s.

Napa County’s unvaccinated and partially vaccinated residents are currently 72 percent more likely to contract the virus, 95 percent more likely to be hospitalized because of it and 97 percent more likely to die, according to county data.

COVID cases among the county’s unvaccinated residents ages 12 and up outnumbered those among fully vaccinated residents by roughly 10-to-one in December.

The majority of the county’s hospitalizations and deaths have also continued to occur in unvaccinated and partially vaccinated residents.

As of Sunday, 78 percent of county residents ages 5 and up have completed their initial vaccination series. Nearly 43,000 residents have also received a booster dose, roughly half of those in the county who are eligible for a booster.

“The boosting part is really important because we’ve been seeing a lot of omicron cases among people that are vaccinated,” Relucio said. “So boosting provides an additional layer of protection against hospitalizations and deaths.”

Relucio noted that the county is not currently considering a return of COVID-related restrictions, even as neighboring Sonoma County announced Monday that it would prohibit large indoor and outdoor gatherings for at least one month amid the omicron wave.

Sonoma County Health Officer Dr. Sundari Mase also urged the county’s residents to only leave their houses for necessary trips to work and school or to buy groceries and seek medical care.

Relucio called Sonoma County’s announcement an “independent decision,” and argued that Napa County’s residents are free to determine their own risk tolerance for now.

“At this point, it’s a matter of people choosing what they’re going to do and assessing the risks,” she said.