The CDC recommends that people avoid travel on cruise ships, including river cruises, worldwide if they are not vaccinated. This is especially important if they are at increased risk of severe illness. That’s because the risk of COVID-19 on cruise ships is high. Learn more about cruise ships and river cruise voyages. Safety is one of the top priorities for nations worldwide, be it in better protecting its citizens on the streets, guarding them against wrongdoing or even safeguarding them against online crime.