The U.S. Centers for Disease Control and Prevention (CDC) has begun a key step for the eventual resumption of U.S. cruise industry operations by issuing new technical instructions. In October, the CDC issued Conditional Sailing Order for operators, which acted as a guidance for a phased resumption of cruise ship passenger operations. On Wednesday, it announced two new phases and said operators now have all necessary requirements needed "to start simulated voyages before resuming restricted passenger voyages and apply for a COVID-19 conditional sailing certificate to begin sailing with restricted passenger voyages." The CDC said on April 28 it was "committed" to the resumption of cruise industry passenger operations by mid-summer as it issued some clarifications of its earlier order.The agency also released the COVID-19 Conditional Sailing Certificate application, "the final step before restricted passenger voyages." The new guidance includes eligibility and requirements for conducting a trial voyage in preparation for restricted passenger voyages and for CDC cruise ships inspections during simulated and restricted passenger voyages. Once cruise ships operators receive approved COVID-19 Conditional Sailing Certificate applications, they will be permitted to sail with passengers. The Cruise Lines International Association, which represents Carnival Corp (CCL.N), Norwegian Cruise Line (NCLH.N) and Royal Caribbean Cruises (RCL.N), said Wednesday it was reviewing the CDC"s latest instructions. The association said last week it was optimistic that CDC "clarifications show positive progression—and, importantly, a demonstrated commitment to constructive dialogue, which is key to restarting cruising."The group added "plenty of work remains in order to achieve our mutual goal of responsible resumption from U.S. ports this summer." Florida and Alaska have filed a lawsuit seeking to force the CDC to immediately allow the resumption of cruise operations. The CDC said COVID-19 vaccines "play a critical role in the safe resumption of passenger operations, but not all cruise ship operators have announced plans to mandate passenger vaccinations." The agency said it "recommends that all port personnel and travelers (passengers and crew) get a COVID-19 vaccine."