Federal health officials are dropping the warning they have attached to cruising since the beginning of the pandemic, leaving it up to vacationers to decide whether they feel safe getting on a ship.

Cruise-ship operators welcomed Wednesday's announcement, which came as many people thought about summer vacation plans.

An industry trade group said the move by the Centers for Disease Control and Prevention validated measures that ship owners have taken, including requiring crew members and most passengers to be vaccinated against the virus.

The CDC removed the COVID-19 "cruise ship travel health notice" that was first imposed in March 2020, after virus outbreaks on several ships around the world.

However, the agency expressed reservations about cruising.

"While cruising will always pose some risk of COVID-19 transmission, travelers will make their own risk assessment when choosing to travel on a cruise ship, much like they do in all other travel settings," CDC spokesman Dave Daigle said in an email.

Daigle said the CDC's decision was based on "the current state of the pandemic and decreases in COVID-19 cases onboard cruise ships over the past several weeks."

COVID-19 cases in the United States have been falling since mid-January, although the decline has slowed in recent weeks, and the current seven-day rolling average for daily new cases in the U.S. is roughly unchanged from two weeks ago, according to figures from Johns Hopkins University. States have rolled back mask mandates, putting pressure on federal officials to ease virus-related restrictions.

Outbreaks continue to be reported on cruise ships, which conduct random testing before the end of voyages.

On Sunday, a Princess Cruises ship returning from the Panama Canal had "multiple" passengers who had tested positive for the virus. Princess Cruises said all the affected passengers showed mild symptoms or none at all, and that all crew members and passengers had been vaccinated. About a dozen passengers tested positive before the same boat docked in San Francisco in January.

Operators are required to tell the CDC about virus cases on board ships. The agency has a colored-coded system to classify ships based on the percentage of passengers who test positive. The CDC said that system remains in place.

Cruise-ship operators have complained since the start of the pandemic that their industry has been singled out for a shutdown and then tighter COVID-19 restrictions than others, including airlines.

The Cruise Lines International Association said in a statement that the CDC's decision to remove its health warning "recognizes the effective public health measures in place on cruise ships and begins to level the playing field between cruise and similarly situated venues on land."

Colleen McDaniel, editor in chief of Cruise Critic, a site that publishes review of trips, called the CDC decision big news.

"Symbolically it's a notice of winds of change when it comes to cruising," she said. "I do think it can convince some of the doubters. What the CDC says does matter to cruisers."