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SAN DIEGO — The first omicron COVID-19 case in San Diego County has been identified, local health officials announced Thursday.

The San Diego resident, who tested positive for COVID-19 Wednesday, had recently traveled abroad, the County Health and Human Services Agency said. The omicron variant was identified Thursday morning after the San Diego Epidemiology and Research for COVID Health (SEARCH) Alliance conducted whole genome sequencing.

The patient had been vaccinated and received a booster. The individual was not hospitalized and is under isolation.

“When we do sequencing, what we are literally doing is we are reading off every location on that viral genome like letters in an alphabet,” said Dr. Louise Laurent, a professor at the UC San Diego School of Medicine and co-lead of SEARCH. “We can compare that to the other known variants then we can see that omicron is unique it has a very special sequence or pattern.”

Speaking to FOX 5 Thursday, Gov. Gavin Newsom said that as of Wednesday night, the state had identified 13 cases of the COVID omicron variant, “but we know it’s exponentially higher than that.”

The county is working to identify people who may have come into close contact with the individual.

“We expected that the omicron variant would make its way to San Diego, and it has,” said Wilma J. Wooten, M.D., M.P.H., county public health officer. “We are continuing to monitor for the omicron variant and will report any other cases to the public when they are identified.”

According to Sharp HealthCare Family Medicine Dr. Abisola Olulade, the reason omicron drew such concern was due to its quick spread. The variant first was detected in South Africa, but experts still don’t know where the variant originated from.

“It was spreading very rapidly,” Olulade said. “They started to detect it in many people and actually it spread over a very short period of time.”

As the holidays approach, Olulade said people should double down on measures they were taking at the start of the pandemic. She recommends everyone to get vaccinated and get a booster shot, to wear a mask in highly populated areas, and to consider meeting outside for large holiday gatherings.

FOX 5‘s Clara Benitez contributed to this report.