SAN DIEGO (KSWB) — A health care worker is San Diego County’s first known case of a fully vaccinated individual to test positive for COVID-19, local health officials said Wednesday.

The positive case was reported this week, Dr. Eric McDonald, medical director of the County Epidemiology and Immunization Services branch, said at the county’s Wednesday update on efforts to control COVID-19. The health care worker showed minimal symptoms and had known exposure to the virus.

While not the first ever case of a fully vaccinated person to test positive for the virus, it is the first such case reported in San Diego County. Last week, four people in Oregon tested positive for the virus at least two weeks after receiving their vaccines, the Associated Press reported.

“We know that the vaccine is not perfect,” McDonald said. “It is very good at preventing bad outcomes from COVID — that is, death and hospitalization — but a very small percentage of individuals — we would expect, actually even getting their full vaccine — may come down with symptoms and in fact potentially be contagious with others.”

According to the Centers for Disease Control and Prevention, a person can get sick shortly after a vaccination because not enough time has passed for the vaccine to provide protection. This is because it usually takes a few weeks for a vaccinated person to build immunity to the virus.

No details were provided about when the health care worker received their second dose.

“We do expect more, we expect the number to be low and we expect most of the cases to be like the one that was just reported which is essentially minimal symptoms,” McDonald said.