Washington, Dec 29 : Separate Covid-19 outbreaks occurred on board two US Navy warships, infecting a significant number of their respective crews while disrupting their ongoing operations, media reports said. On one of the ships, USS Milwaukee, which was being deployed to intercept drug trafficking in the Caribbean and East Pacific, there were reportedly more than 20 sailors, or roughly one-fourth of its 105 crew members, who tested positive for the virus, the Xinhua news agency quoted the reports citing defence officials as saying. The outbreak forced the littoral combat ship, which set sail from Naval Station Mayport in Jacksonville, Florida, for the ongoing mission on December 14, to remain in port at Naval Station Guantanamo Bay in Cuba, where it stopped to refuel and resupply on December 20. The Navy said in a statement on Friday that the Milwaukee's crew "is 100 per cent immunized", that those who have contracted the virus have been isolated on board and kept away from other crew members, and that "a portion of those infected have exhibited mild symptoms". The New York Times reported that there was no need for hospitalisation for any of the infected, and that the hospital at the Guantanamo Bay base was offering booster shots for sailors on a voluntary basis, as per the request from the Milwaukee. Also, destroyer USS Halsey delayed its homeport move from Pearl Harbor in Hawaii, to San Diego, California, after roughly one-third of its crew got positive test results for Covid-19, the Associated Press (AP) reported, citing Navy Commander Sean Robertson, spokesperson for the 3rd Fleet. Almost all the crew members were vaccinated, and none of the infected was taken to the hospital, Robertson said, adding that booster shots were available for the crew. Robertson also said positive samples that have been tested so far all turn out to be Omicron variant. The Halsey was finally able to leave Hawaii on Sunday. According to the latest data released by the Navy, more than 98 per cent of all active-duty sailors have been fully vaccinated. A total of 5,361 active component sailors remained unvaccinated as of December 22. The Navy put out an updated guidance on December 15 that it would begin discharging sailors who refuse to get vaccinated. /IANS