Updated Sunday at 5:17 p.m. ET

People who are quarantined aboard the Diamond Princess in Japan have been wondering how long their situation would last. On Sunday, the World Health Organization offered clarity on that question.

The coronavirus quarantine that has kept some 3,700 people aboard the cruise ship is set to end on Feb. 19. However, for "close contacts" of infected passengers, the quarantine will be extended 14 days from the last contact with a confirmed case, according to the WHO.

An additional 41 cases were confirmed on board early Friday, bringing the total among passengers and crew to 61. Those samples were part of the initial screening — meaning those confirmations didn't require a new 14-day quarantine to begin.

Then on Saturday, officials announced they had confirmed three more cases, for a total of 64.

Princess Cruises had announced that the previous group would end their quarantine on Feb. 19. Among those people, Japan's health ministry had taken samples from just 273 individuals who were deemed to be in an at-risk group, based on their recent travels.

Before the latest announcement, some of the passengers spoke with NPR.

"I've been very relaxed," Philip Courter of Florida said of the quarantine's early days, in an phone interview with NPR's Rebecca Davis. But he added that he is starting to get nervous: "If more and more and more people are getting sick on this ship, what are we doing here? This is crazy."

If the cruise ship were a country, it could already claim the second-highest number of coronavirus cases outside of mainland China. Now passengers are hoping no new cases emerge.

"It is difficult for people who get caught up in that situation, because they are confined," Dr. Michael Ryan, executive director of the World Health Organization's emergencies program, said at a Friday news conference. While the quarantined passengers' physical health is at risk, he said their mental health should also be supported.

"It's quite scary — very, very scary — to be in that situation," Ryan said.

The WHO has been working with Japanese officials to devise a way to organize the passengers into cohorts, Ryan said. The idea is that in smaller groups, fewer people would be affected when a new patient is identified.

The WHO position adds clarity to circumstances aboard the cruise ship, which is docked at Japan's Yokohama port.

On the ship, passengers — including some who had already spent two weeks aboard the vessel before the quarantine doubled their stay — are told not to leave their rooms. They visit the deck in shifts, for a rare breath of fresh air.

"My concerns are what happens next," passenger Aun Na Tan of Australia, told NPR's Rebecca Davis via text message. "We don't have a clear plan of what is going to happen," she added, citing the risk of new cases.

Tan, who has been posting messages to social media about her experience on the cruise ship, was on a trip along with her husband, daughter and one of her two sons when their vacation was unexpectedly extended by the quarantine.

Despite her worries about how long her family will have to wait before they can leave the ship and resume their normal lives in Melbourne, Tan said she doesn't have any complaints about the way they're being treated during the quarantine.

"I'm not worried about our quarantine on board," she wrote, adding that with care of the crew, "we are in good hands here."

Still, Tan and other passengers hinted at some frustration about being in quarantine.

At least 10 Americans are among the people who have tested positive for the coronavirus. The patients have been taken to local hospitals. Most of them are from Japan, but some are from Canada, Australia and other countries.

The coronavirus is now blamed for more than 811 deaths in mainland China, surpassing the number of global fatalities recorded during the SARS epidemic between 2002 and 2003.

To detect any new cases aboard the ship, the crew has distributed thermometers to passengers so they can monitor themselves. To ease the strain of prolonged isolation, Princess Cruises says it has been providing complimentary Internet and phone service to let passengers stay in touch with loved ones. It has also expanded its TV and movie options — and it says the ship's activities staff is bringing games, puzzles and other distractions to passengers' rooms.

Tan and her family were able to get some fresh air on Friday afternoon, after spending all of Wednesday and Thursday in their room. Because they're in an inner room, she said, they got to visit the outdoors before passengers in outer rooms who have windows looking out onto the sea.

"This is the first time we have been out since quarantine started on Tuesday night," she said.

Sawyer Smith / via Reuters

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via Reuters

Tan's family joined about 50 other people — all of them passengers in odd-numbered rooms in the inner tier on her floor.

"It was kinda strange being outside," she said. And definitely was great enjoying the fresh air. Being inside without windows, you lose track of time."

Passengers are asked to follow several rules when they visit the deck, Tan said.

"We were asked to wear masks and gloves, not to come closer than 1m (about 3 feet) to anyone else. To wash our hands with soap and water when we return to our room."

Each group gets 90 minutes outside, and there's a 30-minute gap between them. The last passengers come in at 7:30 p.m., she said.

Because of the large number of people and the need for them to visit the deck in shifts, some of her fellow passengers still hadn't visited the outdoors by late Friday, Tan said.

As for how her family is coping with being confined to a windowless room for days on end, Tan said they're "pretty close" and can share space. Plus, she said, "My kids are happy to just put on headphones to zone us out lol."

NPR's Rebecca Davis and Jane Greenhalgh contributed to this report.

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