The Centers for Disease Control and Prevention said Friday that travelers who are at high risk of severe complications from Covid-19 should avoid taking cruises, regardless of their vaccination status.
The updated guidance also recommended that travelers who are not fully vaccinated avoid taking cruises.
The new advice follows several coronavirus outbreaks that have been reported aboard cruise ships, according to the CDC.
In addition, although the agency is not putting in place the same type of masking requirements that exist for planes, trains and other public transportation, it suggested cruise passengers wear a face covering in shared spaces.
"The virus that causes Covid-19 spreads easily between people in close quarters aboard ships, and the chance of getting Covid-19 on cruise ships is high," the CDC said in its updated guidance.
The agency advised all travelers to get tested one to three days before taking a cruise and three to five days after returning, regardless of their vaccination status. Those who take a cruise should also quarantine for seven days after returning, even if they test negative for the virus.
The new guidance comes just a week after the Belize Tourism Board announced that 27 people aboard a Carnival cruise tested positive for Covid.
During extended trading on Friday, shares of Carnival Cruises fell more than 2%, shares of Norwegian Cruise Line fell nearly 3% and shares of Royal Caribbean Cruises fell more than 2%.
After the industry was shut down at the beginning of the pandemic due to several outbreaks aboard ships, the CDC has been enforcing strict guidelines to prevent similar events.
Of the three cruise operators, Royal Caribbean was first to return to operations and has had few cases aboard ships, which CEO and Chairman Richard Fain said was the goal.
Royal Caribbean and Carnival have been allowing some unvaccinated passengers aboard ships, but Norwegian has not.
Norwegian even filed a lawsuit against the Florida surgeon general to stop a state ban that prevented businesses from requiring customers to show proof of Covid vaccination. The cruise operator was granted a temporary halt on the enforcement of the law, but Florida has filed an appeal.
