SACRAMENTO COUNTY, Calif. (KTXL) — Sacramento County has confirmed its first cases of the COVID-19 omicron variant.

Two Sacramento County residents have tested positive for the new dominant variant, the county confirmed Tuesday.

Only one of the infected residents is vaccinated.

One of the residents had mild symptoms, while the county said the other is asymptomatic.

There is no history of recent travel between the two.

“Getting vaccinated, getting a booster when eligible, getting tested and following local mask guidance are the most important things people can do to prevent the spread of COVID-19, including the Omicron variant. If you are vaccinated and planning to travel or gather, it’s recommended that you get tested one to three days prior to and three to five days after traveling or gathering,” the county wrote in its release.

Traces of the variant were discovered in samples from a wastewater treatment plant in Elk Grove earlier this month.

Based on those findings alone, Marlene Wolfe, an assistant professor of environmental health at Emory University in Georgia, was able to give a ballpark estimate as to how many cases were in the area.

“We would estimate that if we are detecting something, that would mean there are on the order of 10 to 20 cases, and that’s an estimate,” Wolfe told FOX40 at the time. 

Two weeks ago, Sacramento County’s epidemiology program manager, Jamie White, said public health officials assumed omicron cases were already present in the county. However, not all COVID-19 samples are tested to determine the variant. 

“So they probably exist, we just haven’t gotten one yet,” White explained.

Sacramento County’s seven-day average case rate per 100,000 people stood at 13.8 as of last Friday.

Testing has revealed over 8,000 delta variant cases in the county, far more than any other variant.

But scientists say omicron spreads even easier than other coronavirus strains, including delta. Early studies suggest the vaccinated will need a booster shot for the best chance at preventing an omicron infection but even without the extra dose, vaccination still should offer strong protection against severe illness and death.

The Associated Press contributed to this report.