A Holland America Line cruise ship was denied entry to a Mexican port over the weekend after health officials discovered positive COVID-19 cases on board.

The Mexican state of Jalisco’s health department confirmed in a statement to media outlets that 21 crew members on the Koningsdam cruise line tested positive for the CCP (Chinese Communist Party) virus, which causes COVID-19 when it arrived in the tourist resort city of Puerto Vallarta.

“Through onboard testing, we have confirmed that a small number of fully-vaccinated crew on Koningsdam tested positive for COVID-19,” Holland America wrote in a statement on Saturday to news outlets. “All are showing mild or no symptoms and are in isolation. Close contacts have been quarantined out of an abundance of caution.”

According to the Jalisco health department, the entire crew was tested for COVID-19 before departure on Dec. 19. Only one positive case was discovered.

“Due to a last-minute notification from authorities that guests would not be permitted ashore, the ship departed and will return to San Diego to arrive in two days as scheduled,” Holland America also said in a statement provided to KNSD-TV. “Guests were notified and continue to enjoy activities aboard the vessel.”

Holland America’s website says that patrons and staff have to be fully vaccinated, as well as provide a negative COVID-19 test in order to board its ships. The cruise line also mandates that guests and staff have to wear masks inside.

The Epoch Times has contacted Holland America for comment.

Several days before that, Royal Caribbean’s Odyssey of the Seas did not disembark at two Caribbean locations, according to the cruise operator in a statement to The Epoch Times.

“Royal Caribbean International’s Odyssey of the Seas will not visit Curacao or Aruba as planned,” the cruise line told The Epoch Times. “The decision was made together with the islands out of an abundance of caution due to the current trend of COVID-19 cases in the destinations’ communities as well as crew and guests testing positive on board–55 crew members and guests, representing 1.1 percent of the onboard community.”

“The cruise sailed with 95 percent of the onboard community fully vaccinated.”

It’s not clear if the Omicron variant triggered the outbreak on either of the two ships. The Centers for Disease Control and Prevention (CDC) estimated that as of last week, Omicron made up 73 percent of all COVID-19 cases.

Meanwhile, recent studies have signaled that the new CCP virus strain causes milder symptoms and has resulted in far fewer hospitalizations worldwide. Only one death has been associated with the new strain in the United States—in Houston, Texas.