A cruise ship traveling between Hawaii and San Francisco this month experienced a COVID-19 outbreak, health officials said.

The San Francisco Department of Public Health confirmed there were 143 passengers aboard the Ruby Princess cruise ship who tested positive for the coronavirus during a round trip from San Francisco to Hawaii and back that ended April 11.

According to The Mercury News, “scores of passengers” aboard the Ruby Princess became sick and tested positive for COVID-19.

This coronavirus outbreak followed another one on the Ruby Princess during a trip between San Francisco to Panama on March 27, where more than 70 had been reported sick with COVID-19.

The Hawaii Department of Transportation said Ruby Princess docked in Honolulu on April 1, Kahului on April 2, Nawiliwili on April 3, and Hilo on April 4, according to its itinerary.

The vaccination rate for the Ruby Princess’s April 11 trip was 100% for both crew and guests, according to SFDPH. Most people who tested positive experienced mild or no symptoms, but one was hospitalized.

“Only one person on the April 11 trip was hospitalized, which speaks to the incredible efficacy of vaccination,” said SFDPH in a statement.

On a more recent trip, the Ruby Princess returned to San Francisco Saturday with 37 cases of COVID-19 on board, the department said.

The SFDPH says it has memoranda of agreements with cruise operations that establish clear protocols for all vessels that embark, disembark, and transit through San Francisco.

Cruise lines must report confirmed or suspected cases to SFDPH 24 hours prior to arrival in the Port of San Francisco, in addition to information on the percentage of people on the vessel who are vaccinated, and the number of passengers who will disembark to finish their isolation or be hospitalized in the Bay Area

The U.S. Centers for Disease Control and Prevention lists the Ruby Princess — owned and operated by Princess Cruises under the Carnival Corp. — as orange, which means it meets criteria requiring an investigation.

On March 30, CDC removed its COVID-19 cruise ship travel health notice, leaving it up to travelers to make their own risk assessments.

During the height of the omicron surge in late December, CDC had issued a “level 4” warning that recommended avoiding cruise travel regardless of vaccination status. Cruise ships returned to Hawaii after a nearly two-hear hiatus in early January, when the “level 4” warning was still in place.

When the travel health notice was dropped on March 30, CDC had rated cruise travel as “level 2,” or moderate.

The Ruby Princess’ next visit to Honolulu is scheduled for Oct. 15.