A US cruise line just announced a vaccine requirement. These are all the cruise lines that will require COVID-19 vaccinations for guests and crew bchang@businessinsider.com (Brittany Chang) The return of cruising still remains in limbo for many cruise lines. Companies including Royal Caribbean and Norwegian have announced vaccine requirements. These are all the cruise lines that have COVID-19 vaccine requirements for guests or crew. Several cruise lines have started announcing vaccination requirements for guests and crew members as the industry looks to restart after the the COVID-19 pandemic. Last year, cruise ships that were mid-trip began facing COVID-19 related turmoils as the virus began trickling around the world, leaving passengers stuck, infected, or dead. Shortly after, the US Centers for Disease Control and Prevention issued a no-sail order, which was later replaced by its "Framework for Conditional Sailing Order," a compilation of protocols needed for cruising to resume again.