Not sure the FAQ really answers anything:
Should I be concerned if a cruise ship status is “Orange” or “Yellow”?
CDC acknowledges that it is not possible for cruising to be a zero-risk activity for spread of COVID-19. Cruising will always pose some risk of COVID-19 transmission. Therefore, public health measures, including testing and vaccinations, will continue to play a role. CDC recommends that all travelers (passengers and crew) get fully vaccinated against COVID-19. CDC recommends that people who are not fully vaccinated avoid travel on cruise ships, including river cruis