SAN FRANCISCO, Calif. (KRON) — The Ruby Princess returned to San Francisco Sunday from a 15-day Panama Canal cruise with some passengers and crew members infected with COVID-19.

“During the cruise we identified some positive COVID-19 cases amongst our guests and crew members,” a Princess Cruises spokesperson told KRON4.

All guests and crew on the ship were fully vaccinated, the cruise line said, and those infected were either asymptomatic or showed mild symptoms.

The total number of infections resulting from the cruise was not released.

The ship’s medical team ordered everyone who tested positive to isolate.

“In collaboration with CDC and San Francisco Department of Public Health, those guests who tested positive and have not completed the isolation period will either return home via private transportation or were provided with accommodations ashore to hotels coordinated in advance for isolation and quarantine,” the cruise line wrote.

Ruby Princess is scheduled to depart San Francisco Monday afternoon for a 15-day cruise to Hawaii.

Cruise ships were sources of “super-spreaders” for the San Francisco Bay Area early on in the pandemic.

The CDC’s current COVID warning for cruise travel is Level 2, meaning, “moderate” health risk.