As many as two dozen sailors onboard the U.S. Navy’s USS Milwaukee warship have tested positive for COVID-19, forcing it to remain at Naval Station Guantanamo Bay in Cuba as of Monday.

The ship, which has more than 100 crew members, had a COVID outbreak last week that is continuing. The number of infected seamen is staying relatively consistent, defense officials anonymously told the Associated Press.

According to the Navy, the USS Milwaukee crew is “100% immunized,” and all crewmembers who tested positive for COVID-19 are being isolated on the ship.

Navy officials said in a statement that “a portion” of crewmembers infected with the virus have mild symptoms. It was unclear which variant of COVID-19 the crew were infected with.

Officials also said they believe full vaccination of the crew was the main factor in controlling the outbreak onboard the ship, the AP said.

The USS Milwaukee has had to interrupt its deployment, which began Dec. 14 from the Naval Station in Jacksonville, Florida. The ship was headed to the U.S. Southern Command region, the AP reported.

This is not the first COVID outbreak for the Navy this month as the USS Halsey destroyer delayed a homeport trip from Pearl Harbor to San Diego, California, due to one-third of its 300-member crew testing positive for the virus. The ship was finally able to depart on Sunday, the AP said.

Navy officials told the news outlet that most USS Halsey crewmembers were fully vaccinated and had mild to no symptoms. No one was hospitalized, and all crew infections were the Omicron variant, the officials added.

The Navy has required all sailors to be fully vaccinated as part of a military mandate set forth by the Biden administration.

According to data from the Navy, more than 95% of all active-duty seamen are fully vaccinated, and more than 99% of active-duty forces have received one shot of the COVID vaccine. The deadline to be fully vaccinated is today, Dec. 28.

A total of 5,361 service members remain unvaccinated, according to the Navy.

A handout photo courtesy of the US Navy's Twitter account on July 25, 2021 shows aircraft carrier USS Ronald Reagan, French navy frigate FS Languedoc, and guided-missile destroyer USS Halsey at sail in the Arabian Sea
The USS Milwaukee was held at the Guantamo naval port after a COVID-19 outbreak among 100% immunized crew members. Representational image of a US warship. US NAVY / -