The CDC wants cruise ships arriving in and departing the U.S. to maintain high Covid-19 vaccination rates and require cruisers to get tested for Covid the day before embarkation, but that's not required, according to a new set of guidelines for cruise ships unveiled on Wednesday.
"A threshold cruise ship operators can consider is operating with at least 90% passengers and 95% crew who are up to date with their Covid-19 vaccines," said a statement from the CDC's guidance in its section of frequently asked questions.
This is a shift from the CDC's previous directive that classified ships based on their vaccination rate such as by "standard of excellence," "highly vaccinated" or "not highly vaccinated." The tiers served to inform potential passengers of the percentage of their fellow travelers who would be vaccinated.
The new guidance replaces the Covid-19 Program for Cruise Ships, which the CDC ended on July 18.
Much of the new guidance is optional. The CDC recommends that cruise lines require guests to undergo pre-embarkation testing no more than three days before a sailing but "highly" recommends that lines require testing within one day of embarkation.
That guidance comes as some cruise companies have indicated plans to stop pre-embarkation testing in the coming weeks, including Azamara and Norwegian Cruise Line Holdings. Both lines indicated the testing would continue if mandated by local destinations -- which had included the U.S. until the CDC's dissolved the Covid-19 program for ships.
The new guidelines also encourage ships to consider suspending operations in the event of sustained transmission of Covid. The CDC recommends using a measure called the "attack rate" to identify the severity of a Covid outbreak.
The rate is calculated using the cumulative number of passenger cases in the last seven days divided by the average number of passengers onboard the ship in the last seven days. It recommends suspending operations if the attack rate for passengers or crew is greater than or equal to 10% at least once weekly over three consecutive weeks; if the attack rate is greater than or equal to 20% for guests or crew on any single day; or if the attack rate for crew and passengers combined is 30% on any single day.
Cruise lines are still required to submit data to the CDC on confirmed Covid-19 and Covid-19-like cases. Ships can submit a daily form, but ships that do not are required to report individual cases of Covid-19. Nonetheless, the CDC said that travelers who want information about Covid-19 cases should contact their cruise line directly.
Outside of the new guidelines, the CDC warned that individual travelers with a medical condition or who take medication that compromises their immune system may not be fully protected when taking a cruise, even if vaccinated, and it suggested that they talk to their healthcare provider.
The CDC also recommended that travelers check directly with their cruise line about Covid testing and vaccination protocols before traveling, and opt to get tested even if the cruise line doesn't require it.