Another COVID outbreak has occurred on a cruise ship, this time with the breakout occurring among crewmembers onboard the Holland America Koningsdam ship that had departed from San Diego on Sunday.

The Koningsdam ship was denied entry into Puerto Vallarta on Dec. 23 by Mexican officials due to the positive cases of the virus and arrived back in San Diego as originally scheduled on Sunday, KSWB, a Fox affiliate out of San Diego, reported.

The ship did stop in Cabo San Lucas and Mazatlan as only one case of COVD-19 was detected among a crewmember before Dec. 23, KFMB, a CBS affiliate out of San Diego, reported.

After disembarking in San Diego, the cruise ship set sail Sunday for another seven-day cruise, according to KFMB.

Erik Elvejord, Holland America’s director of public relations, told KSWB, “With the pervasive nature of the Omicron variant, we have continued to evolve our protocols, which were developed with guidance from leading health experts and in anticipation of situations like this.”

Elvejord continued by saying there were no confirmed COVID cases among passengers on the Koningsdam ship – the largest vessel in the Holland America fleet. More than 1,000 passengers were on board the ship, KSWB said.

Holland America requires proof of vaccination for all crew and guests five years and older and a negative COVID test two days before boarding for all passengers, according to its website.

It was unclear at the time of writing exactly how many crewmembers had tested positive for the virus, but the Daily Mail reported that as many as 21 crewmembers were infected with COVID-19. Holland America said it was a “small” outbreak with all currently quarantined.

Elvejord told KSWB, “The important thing is these crew cases ... are mild or asymptomatic. Our crew are vaccinated and many have already received a booster.”

This is one of a series of COVID outbreaks that have occurred onboard cruise ships this December.

The Carnival’s Carnival Freedom ship had a small number of people test positive for COVID-19 last week, CNN reported, while Royal Caribbean’s Odyssey of the Seas ship had 55 fully vaccinated crew members and passengers test positive for COVID-19 also last week.

The Seven Seas Mariner ship had seven cases of COVID-19 onboard earlier this month, CNN said, and Royal Caribbean’s Symphony of the Seas had at least 48 people onboard test positive for COVID-19 sailing in mid-December.

The Holland America cruise ship Zaandam arrives at Port Everglades in Fort Lauderdale, Florida
The Holland America cruise ship Zaandam arrives at Port Everglades in Fort Lauderdale, Florida AFP / CHANDAN KHANNA