KEY WEST, Fla. >> Days after a harrowing journey to escape a trans-Atlantic cruise where two passengers came down with fatal cases of COVID-19, Jim Nevis is back home in Arizona, fighting the virus in a hospital intensive care unit.

A Canadian family that evacuated from the same Italian ship, the Costa Luminosa, traveled through three airports to get home to Victoria, British Columbia, only to learn that all five of them were infected. Michelle Saunders, who was on the Grand Princess when it docked March 9 in Oakland, Calif., was quarantined on an Air Force base in Georgia, then released two days early with a warning that she and the others could still become ill and possibly make others sick, too

Then on Friday, Holland America Line announced that four passengers had died aboard its cruise ship, the Zaandam, after it was refused entry into Chile nearly two weeks ago. The ship, with 53 passengers and 85 crew members aboard displaying symptoms of the coronavirus, was denied permission to transit the Panama Canal and sail on to Fort Lauderdale, Fla.

What would happen to the passengers if they reached Florida was far from clear.

With at least 18 cruise ships still at sea and making their way to shore in the coming days, state and federal authorities have yet to establish a cohesive strategy for evacuating ships and repatriating passengers around the world without exposing them and others to more disease.

Passengers who were either sick or possibly exposed to the virus were in some cases put on buses and planes, endangering others. Quarantine procedures for evacuees were sometimes contradictory and confusing, as the problems of holding passengers in isolation after they returned from their trips became almost as substantial as the danger of letting them go.

“The evacuation definitely helped sicken people and definitely helped spread the disease,” said Paul Turner, a golf club professional in Wisconsin who was aboard the Costa Luminosa.

The ship, which set out from Fort Lauderdale bound for Venice, Italy, tried to dock at several ports before unloading in Marseille, France, on March 19. Turner and the other Americans and Canadians on board flew to Atlanta, then made their way to their home destinations.

While U.S. health authorities took great pains to sequester passengers from affected cruise ships in the early days of the outbreak, the Centers for Disease Control and Prevention in recent days has allowed hundreds of exposed and ill cruise passengers to travel on commercial flights across the country, potentially jeopardizing everyone from flight attendants to airport restaurant workers, to unwitting fellow passengers.

The reason, CDC officials said, is that the outbreak has entered a “new phase” in which so many people are returning from countries affected by the virus that the priority is to get evacuated passengers home quickly, where they can self-isolate.

“We are at a different stage of a pandemic,” said Benjamin Haynes, a CDC spokesman. “We are doing our best to not allow sick people to get on commercial airlines. But we also have an urgency to return well travelers home as quickly as possible.”

William Burke, the chief maritime officer for Carnival Corp., which operates more than 100 cruise vessels around the world, said companies were facing suddenly closed ports, or countries that have abruptly imposed new border rules in response to the coronavirus.

“This week the rules are different than they were a week ago,” Burke said. “We learned a lot about how to do this, good and bad. I wish I had learned from somebody else doing it.”

Passengers who were part of the chaotic scramble over the past 10 days, under rules that allowed many passengers to navigate their own way home, said that even people who were coughing and clearly sick were packed into buses and planes.

Nevis, who flew from Atlanta to Phoenix, learned this week that he had COVID-19.

“We were lepers — roaming freely,” said Jane Kennedy, who flew to Iowa after sailing on the Costa Luminosa. “God knows how many people we infected.”

James Walker, a lawyer who files lawsuits against cruise companies, said the federal authorities still lack a plan for how to get people home safely.

“I don’t think the CDC has protocols in place,” Walker said. “Everyone is scrambling around trying to figure things out. It seems to me kind of a Mad Hatter type of environment; no one who is in charge, no one who is taking the lead.”

The cruise ship industry’s battle with the coronavirus erupted in February with an outbreak aboard the Diamond Princess, a vessel owned by Carnival Corp., which was off the coast of Japan. Japanese authorities decided to quarantine the vessel, but at least 700 people got sick and nine died.

The Grand Princess, which in February embarked on a 15-day cruise around the Hawaiian Islands, was diverted to Oakland this month after 21 people fell ill. The authorities evacuated nearly 2,000 asymptomatic people off the ship and took them to military bases in three states, where they complained of unsanitary conditions. Ultimately, 103 passengers tested positive for the coronavirus, and two died.

The U.S. government warned against cruise ship travel on March 8, and a few days later, cruise companies suspended operations worldwide. But 40 ships were still at sea, and few countries wanted them. Port after port refused the ships entry, and many countries closed their borders, which complicated efforts to send people home.

One ship, the Coral Princess, which left Chile on March 5, is now making a two-week journey from Uruguay to Fort Lauderdale without making any of its scheduled stops simply because no other country will let its passengers off, even though none are sick, Princess Cruises said.

The Zandaam had been assured its passengers could disembark in Punta Arenas, Chile, on March 14, Holland America said. But Chile closed its borders and reneged, forcing the ship to make a two-week voyage to Fort Lauderdale. By March 22, passengers started to get sick.

Today, a massive evacuation plan was announced to remove the healthy passengers and place them aboard another ship, the Rotterdam, which arrived from Mexico with doctors, COVID-19 tests and medical supplies.

The Costa Luminosa, also a Carnival ship, left Fort Lauderdale on March 5 and dropped off a passenger with flulike symptoms in Puerto Rico three days later, where the passenger subsequently died of COVID-19. The ship continued on to France. Meanwhile, another passenger who had gotten off the ship earlier with heart troubles in Grand Cayman also died of COVID-19.

Carnival put more than 300 Americans and Canadians on a charter flight from Marseille to Atlanta last week. The passengers said they were crammed together on a plane that was repeatedly delayed and held on the tarmac for hours once the authorities learned that three passengers on the flight had tested positive.

The sick were separated and the others were met by CDC officials, who performed what some passengers described as a cursory look at their health: a temperature check. People who had been coughing and feverish for days had taken over-the-counter medications and managed to lower their fever, several passengers said.

“We can talk and walk and that means we are OK?” said Turner, the Wisconsin golf pro.

A convoy of emergency vehicles had met the plane at a hangar away from the main terminal at Hartsfield-Jackson International Airport, but the passengers who passed the temperature test were then released into the airport, where they stood in long lines at airline counters and sat for hours at gates. One passenger recorded a video showing a group of them at TGI Fridays.

Fabian de la Fuente, the Canadian man who evacuated with his family from the Costa Luminosa, said they were in the international terminal for at least three hours and had lunch at Buffalo Wild Wings. They flew WestJet to Calgary, Alberta, and were there for four hours before flying home to quarantine in Victoria.

He later developed symptoms and tested positive for the coronavirus.

Many of the passengers knew they were sick, Turner acknowledged, but were so exhausted and hungry after a 24-hour trek without food that they would have said anything to be allowed to leave.

“I needed to get home,” he said.

Alexandra Bisquertt, of Hollywood, Fla., picked her 76-year-old mother up at the airport after her evacuation from the Costa Luminosa. A day later, her mother had a 103-degree temperature and had to be taken by ambulance to the hospital, where she tested positive for the coronavirus.

“What about the flight attendants? What about the taxi and Uber drivers who picked these people up?” Bisquertt said. “They did not let one or two sick people out, they released hundreds.”

Saunders, 24, the passenger who arrived in Oakland aboard the Grand Princess, got home to Illinois on Wednesday after 12 days in quarantine at Dobbins Air Reserve Base, northwest of Atlanta.

“There were two people on my bus that were coughing very heavily, which was a bit concerning,” Saunders said of the ride off the base.

The CDC released people from quarantine on the base several days earlier than the 14 days originally scheduled on the condition that they not take a plane, train or bus to their destination. One passenger said she was in quarantine on the base for just three days. Haynes of the CDC said the agency determined that it could accomplish its goal of limiting the spread of COVID-19 by allowing those under mandatory 14-day quarantine at the three bases in Texas, Georgia and California to finish their quarantine at home.

The CDC said its current protocol, revised since the beginning of the outbreak in the United States, is to “recommend that well travelers continue expeditiously on flights home.” Cruise ship passengers are now considered the same as people undertaking other international travel — it is unadvised except when essential. They are being told to self-isolate for 14 days, said Haynes, the CDC spokesman.

Brian Salerno, the Cruise Lines International Association’s senior vice president for maritime policy, said the repatriations were made more difficult because the passengers came from so many countries.

“People tend to focus on them right now, because they are very prominent, but realize this is a pandemic that is affecting all modes of transportation, every form of public gathering, hotels and restaurants,” he said. “The potential for exposure is in all of these. I am not sure we are that different from normal life.”

© 2020 The New York Times Company