January 4, 2022: On Thursday, the U.S. Centers for Disease Control and Prevention advised people against going on cruises regardless of their vaccination status after a recent increase in positive Covid cases onboard ships as the highly contagious omicron variant sweeps the world. The CDC surged its travel warning for cruises to the highest level as the agency investigates or observes dozens of ships with Covid outbreaks.

Cruise ships operating in U.S. waters reported about 5,000 Covid cases to the CDC between Dec. 15 – 29, a significant spike compared with the first two weeks of the month when 162 cases were reported.

“It is essential that travelers who are at an increased risk of severe illness from COVID-19 avoid travel on cruise ships, which include river cruises, worldwide, regardless of vaccination status,” the agency said.

The CDC guidance is a new blow for an industry devastated during the first year of the pandemic. Royal Caribbean Cruises, Norwegian Cruise Line, and Carnival stocks fell on the news.

The CDC warned that Covid transmits efficiently between people in close quarters on ships, and the chance of catching the virus on a cruise is very high even for people who take vaccines and have received a booster dose.

The CDC advised people who decide to go on a cruise to get vaccinated before their trip and receive a booster dose if eligible. According to the agency, facemasks should also be worn in shared spaces, and passengers who are not fully vaccinated should self-quarantine for five days after travel.

The CDC also said people on a cruise should get tested one to three days before departing and three to five days after their trip, regardless of vaccination status or symptoms. However, many Americans shopping for at-home tests have found shelves in many pharmacies empty amid a nationwide shortage, and lines at clinics are sometimes hours long.

Brian Salerno with the Cruise Lines International Association said the trade group was frustrated by the CDC’s decision.

“We’re disappointed at the CDC’s decision to raise the travel level for a cruise today—especially given the overwhelming level of effectiveness of cruise protocols that are resulting in the significantly lower level of cases on the cruise as compared to land,” said Salerno, senior vice president for maritime policy.

Anne Madison, a spokesperson for the industry group, said the Covid cases identified on cruise ships make up a slim majority of the total population onboard.

About 82,000 Americans are hospitalized with Covid as of Thursday, according to a seven-day average of data from the Department of Health and Human Services, up 17% over the past week.