The person in California who tested positive for the omicron variant of the virus that causes Covid-19 was fully vaccinated, has mild symptoms and is improving, officials said Wednesday.

The patient was otherwise healthy when they returned to the San Francisco Bay Area from traveling in South Africa on Nov. 22, developed symptoms three days later and tested positive for Covid on Nov. 29, according to public health officials in California.

Scientists at the University of California, San Francisco received the patient’s sample around 3 p.m. Pacific time Tuesday and completed the sequencing in about five hours, lab director Dr. Charles Chiu told reporters at a press conference Wednesday with San Francisco Mayor London Breed.

Gov. Gavin Newsom, in a separate briefing Wednesday, said the patient is between 18 and 49 and had not received a booster shot because they were not six months out from their original vaccination course.

“This individual has not been hospitalized,” Newsom said. “The individuals that this individual has come into contact with have not tested positive yet to our knowledge, and we are hopeful of full recovery and expect nothing less based on what we’ve learned.”

The Centers for Disease Control and Prevention has recommended that all U.S. adults get a booster six months after their original Pfizer or Moderna two-dose course, and two months after their single J&J shot.

Dr. Mark Ghaly, California’s Health and Human Services secretary, said the fact that the patient is improving underscores the importance of vaccination.

“We have been talking for months about the fact that vaccinations do one really, really important thing — protect against severe disease, against hospitalization and death,” Ghaly told reporters at the briefing with Newsom. “The evidence that an individual with omicron identified by sequencing actually has mild symptoms, is improving, I think is a testimony to the importance of the vaccinations.”