Contra Costa Health Services officials confirmed Tuesday that three novel coronavirus patients among a group of quarantined international travelers at Travis Air Force Base have been transferred to Contra Costa County for treatment.

All three patients will be quarantined indefinitely while they battle the virus as county health officials aim to minimize the potential for exposure to the public.

The patients were brought to Contra Costa County hospitals due to a lack of space at hospitals closer to the Air Force base in Solano County, according to local health officials. While the three patients have tested positive for the virus, neither has begun exhibiting symptoms like fever or breathing difficulties.

According to Contra Costa Health Services, the cases were part of a group of quarantined travelers who were evacuated from the Princess Diamond cruise ship in Japan.

The Centers for Disease Control and Prevention confirmed Tuesday that, so far, 40 people who were aboard the ship have tested positive for COVID-19, the official medical name for the virus.

"Our county's health care system is prepared to handle COVID-19," Contra Costa County Health Officer Dr. Chris Farnitano said. "We have been working with our hospital partners to follow safety protocols to keep patients and health care workers safe and minimize the risk of the virus spreading in Contra Costa."

According to public health officials, practicing good hygiene is the easiest way to reduce the risk of contracting a virus like COVID-19. That includes washing the hands with soap and water, covering the mouth or nose when coughing or sneezing, avoiding work when sick and avoiding touching mucous membranes like the eyes, mouth and nose with unwashed hands.

People who have traveled to the U.S. from China since Feb. 2 are also asked to self-quarantine for at least two weeks under the guidance of their local public health department.