SAN DIEGO – A Holland America Line cruise ship was on its way back to port on Saturday after Mexican health officials refused to allow guests to disembark in Puerto Vallarta after positive Covid-19 tests on board.

The Mexican state of Jalisco’s health department said 21 crew members aboard the ship tested positive for Covid upon arrival in Puerto Vallarta on Thursday.

He said the potential exposure of the passengers means they would not be allowed to disembark.

“Through onboard testing, we have confirmed that a small number of fully vaccinated crews in Koningsdam have tested positive for COVID-19,” Holland America said in a statement. “All have mild or no symptoms and are isolated. Close contacts have been quarantined as a precaution. “

The cruise line said the ship left Puerto Vallarta following a last-minute notification from authorities that the customer would not be allowed to disembark.

The ship was due to return to San Diego on Sunday, the cruise line said.

The ship has 874 crew and 1,035 passengers and was on a cruise that included stops in Cabo San Lucas and Mazatlán, Jalisco health officials said.

They said a crew member tested positive on December 18 and the ship left San Diego the next day. It is not known if this crew member was on board.

Passengers must present full proof of vaccination and a negative Covid-19 test performed within two days of boarding the ship, in accordance with cruise line health and safety guidelines.

It is not known how local health authorities will handle cases after the ship returns. The county health department did not immediately respond to a request for comment.

The Port of San Diego website does not have any protocol information listed for travelers in such a situation.

The port resumed cruises amid a drop in the number of pandemic cases on October 1.

The outbreak came as the Florida-based cruise ship Carnival Freedom was denied entry to Bonaire and Aruba following an undisclosed number of Covid cases aboard the ship, Carnival said in a press release on Friday.

Passengers were to be vaccinated and were tested before leaving, the cruise line said. The ship, carrying 2,497 passengers and 1,112 crew members, was due in Miami on Sunday after eight days at sea.

It was the third outbreak this week affecting cruise ships that had left Florida.

Kurt chirbas contributed.