TOKYO — For a moment on Thursday, John and Carol Montgomery thought they might be departing early from the cruise ship quarantined in Yokohama, Japan, where new cases of the coronavirus have been confirmed almost daily.
Japan’s health minister said a few categories of passengers could spend the remainder of the two-week quarantine ashore. The Montgomerys thought they qualified because they share a cabin without windows or a balcony and John Montgomery, 68, has diabetes.
Their hopes were quickly dashed. The health minister’s statement, it turned out, had been ambiguous. The captain of the vessel, the Diamond Princess, announced narrower criteria for offshore quarantine: passengers 80 or older with underlying medical conditions or windowless cabins.
“Looks like we’re not going anywhere,” said Carol Montgomery, 67.
The misunderstanding punctuated what critics call Japan’s bungled communications during the crisis, reinforcing how the nation has been vexed by an epidemiological challenge that grows each day. With more and more of the Diamond Princess’ 3,400 anxious passengers and crew getting sick — possibly infecting one another — health officials have even raised the possibility of prolonging the quarantine, now set to expire next Wednesday.
Precisely how the coronavirus has been spreading aboard the ship is just one of many unknowns in the affliction’s reach into Japan. The country also announced its first death from the coronavirus, of a woman in her 80s in Kanagawa prefecture, which includes Yokohama.
The authorities said the woman did not appear to have traveled to China, the center of the epidemic, before falling ill. Her death was the third so far outside mainland China; the others were in the Philippines and Hong Kong.
Japan’s health ministry also announced 44 new coronavirus cases from the ship, raising the total to 218. Counting those from the vessel, total cases in Japan have surpassed 250, the most of any country other than China.
The clumsy messaging aside, the move by the health ministry to begin letting some people off the Diamond Princess was clearly a response to mounting stress on board as the quarantine slogs toward its planned conclusion in less than a week. The step also reflected the particular risk that the virus appears to pose to the elderly.
“People in the ship’s surroundings are kind of in a cesspool of probability of being infected,” said Dr. Peter Katona, an infectious disease specialist at the University of California, Los Angeles.
“We don’t really understand the transmission of this virus very well,” he added. “So I think that keeping people in their rooms and letting them out briefly is about as good as you are going to be able to do on a ship, but the psychological impact of that is hard to measure.”
The health minister, Katsunobu Kato, said the government would consider expanding the criteria to include passengers under 80 years old in the coming days.
According to a document distributed to several embassies by Japan’s foreign ministry and seen by The New York Times, the Japanese government is discussing plans to administer coronavirus tests to people aboard the ship in tranches to determine if more can be quarantined onshore. Some passengers have been calling for testing of everyone on board, a step the government has called impractical.
Their psychological stress worsened on Thursday as the health ministry announced the new cases. The authorities have said that a small number of the 218 infected are in serious condition.
“I have worked hard to stay calm, but now it’s getting so much harder,” Sarah Arana, 52, a medical social worker from Paso Robles, California, said in a text message. “It appears that we are put at risk daily by staying on the ship.”
Some epidemiologists said it was possible that the bulk of the people receiving diagnoses now had contracted the virus before the quarantine began on Feb. 4. The outbreak has been traced to a man who disembarked from the ship on Jan. 25 in Hong Kong and later tested positive.
For more than a week after his departure, passengers shared buffets, sat close to each other in theater performances and played mahjong on deck.
“The curve you’re seeing is a natural epidemiological wave,” said Dr. Allen Cheng, an infectious disease specialist at Monash University in Melbourne, Australia. “The first person may have infected a number of people, and those secondary cases have caused tertiary cases, and what we’re seeing now is the natural incubation of those tertiary cases.”
With crew members living and eating in close quarters, the chances for new infections rises the longer everyone stays on the ship. The danger was underlined on Wednesday when the health ministry announced that one of its own officials had been infected after helping to evaluate passengers and crew members for symptoms. The official had been wearing a mask and gloves but not a hazardous materials suit.
“There is a possibility that infections have spread despite the fact that passengers have been isolated on board,” said Mitsuyoshi Urashima, a professor of molecular epidemiology at Jikei University Hospital in Tokyo. “It’s better to let them off, as we don’t know the cause of infection at this stage.”
Passengers were growing concerned that the longer they stayed on board, the longer the quarantine could be extended for passengers who are potentially exposed to confirmed infections.
“The logic and the basis for the quarantine is that if people do not have a fever or show signs of sickness after 14 days, that they don’t have the virus,” John Montgomery, the passenger, said. “But the problem is, on this petri dish of a ship, is that three days prior to the 19th, we may have an interaction with somebody in the hallway or on the deck” who is infected.
On Wednesday, he said, when the couple went out for a prescribed fresh air break, another passenger was coughing in the hallway as they returned to their cabin.
“So this whole thing is based on a false logic,” he said.
In a briefing earlier this week, Masami Sakoi, a health ministry official, said it was possible that people exposed to infected passengers would have to effectively reset the clocks on their quarantine periods.
Carol Montgomery suggested that the governments of the countries with passengers or crew members on the Diamond Princess should offer to house people in quarantine facilities on land.
“If the U.S. Embassy took the Americans off and took us away from here and quarantined and tested us and they did that with every nationality, I think that would be more effective,” she said.
Even so, finding space where such a large number of people could be safely isolated and given proper medical care could be a challenge, especially as Japan is now seeing fresh cases elsewhere. On Thursday, the health ministry announced three new cases, involving a taxi driver and a doctor, in addition to the death from the coronavirus.
“With those waves of new infections every day, that would challenge the most resilient person’s sense of security,” said Benjamin Cowie, an infectious disease physician at the Peter Doherty Institute for Infection and Immunity in Melbourne. “But that’s a very substantial number of people to then try to have to quarantine anywhere on the shore.”
Even with the rising stress, some passengers were making the best of their time trapped on board. Aun Na Tan, 43, an administrator from Australia who is sharing a windowless cabin with her husband, 44, and two teenage children, said they were playing card games and watching movies together while her husband works remotely and her children keep up with homework online.
In such close quarters, Tan said, “my daughter hops into my bed for a cuddle every now and then. I’m just enjoying the opportunity. They get less and less as she gets older.”
Even some who might be eligible to quarantine off shore said they would stick it out on the ship.
“Luckily, we’re staying in a stateroom that’s slightly larger, so we’re fine with it,” said Masako Ishida, 61, who is traveling with her mother and stepfather, who are in their 80s. “We wouldn’t mind at all if we’re the last ones to disembark, as long as those in need can leave the ship. It would be easier if we stayed here until the 19th and relax.”