Updated at 2:25 p.m. ET

Fourteen U.S. passengers evacuated from a cruise ship in Japan and flown to military bases in California and Texas have tested positive for the new coronavirus, U.S. officials confirm.

Earlier, on Sunday, U.S. officials announced that 44 people from the Diamond Princess ship had tested positive for coronavirus. Those who were sick were to remain in Japan to be treated.

The State Department said it was in the process of transporting more than 300 Americans who had been quarantined on the Diamond Princess off Yokohama, Japan, when it got word of the positive tests for the disease now known as COVID-19.

"During the evacuation process, after passengers had disembarked the ship and initiated transport to the airport, U.S. officials received notice that 14 passengers, who had been tested 2-3 days earlier, had tested positive for COVID-19," the State Department said in a joint statement with the Department of Health and Human Services.

The officials said those Americans were separated from the other evacuees, even though the 14 individuals weren't showing symptoms of the virus.

"These individuals were moved in the most expeditious and safe manner to a specialized containment area on the evacuation aircraft to isolate them in accordance with standard protocols," the statement read.

It added: "Passengers that develop symptoms in flight and those with positive test results will remain isolated on the flights and will be transported to an appropriate location for continued isolation and care."

Passengers on the two charter flights landed either at Joint Base San Antonio in Texas or at Travis Air Force Base in Solano County, California, roughly 60 miles northeast of San Francisco.

All passengers will remain under a mandatory a two-week quarantine.

The Diamond Princess has been under Japan-ordered quarantine since Feb. 5, after a passenger who had disembarked earlier tested positive for the virus in Hong Kong. Although Japanese authorities originally said the quarantine period for the ship would expire Wednesday, that date might now be pushed back, NPR's Jason Beaubien reported.

Health officials in Asia say more than 450 people aboard the Diamond Princess have been diagnosed with the coronavirus that emerged in late December in Wuhan, China.

Concerns after passenger on Cambodia ship tests positive

A second cruise ship, the MS Westerdam, docked in Cambodia on Thursday after it was turned away by several other countries. Cruise operator Holland America said passengers and crew were screened for illness and that "there was no indication of COVID-19 on the ship." Cambodian officials allowed people onboard to disembark.

But now an 83-year-old American woman who left the ship and took a flight to Malaysia has tested positive. It's not clear when she became infected, and her positive diagnosis has caused concern that other passengers from the Westerdam might be infected and carrying the virus as they travel home to various countries. The Associated Press reports that the American woman and her husband, who was diagnosed with pneumonia, remain in Malaysia for treatment.

Several hundred passengers from the ship flew out of Cambodia on Friday and Saturday, according to the AP. Some passengers and crew are staying in hotels in Phnom Penh while others are still on the ship.

The latest global numbers

Worldwide, around 71,000 cases of the new coronavirus have been reported and more than 1,700 people — the vast majority of them in mainland China — have died of COVID-19, according to the World Health Organization.

Of the new cases, 94% of them are in China's Hubei province, which has been the center for the outbreak. Outside China, there have been reports of 694 cases, causing three deaths.

Dr. Tedros Adhanom Ghebreyesus, WHO's director-general, said that a new report from China sheds some light on the virus and its severity. The latest data suggests COVID-19 is less deadly than other coronaviruses including SARS and MERS.

"More than 80% of patients have mild disease and will recover," Tedros said in a media briefing on Monday. "In about 14% of cases, the virus causes severe disease, including pneumonia and shortness of breath. And about 5% of patients have critical disease including respiratory failure, septic shock and multi-organ failure. In 2% of reported cases, the virus is fatal, and the risk of death increases the older you are."

Cases of the virus in children are relatively rare, he said, though researchers don't yet know why.

The cruise ship conundrum

As some passengers are taken off the Diamond Princess in Japan, the WHO said during Monday's briefing that cruise ships present unique challenges to controlling infections.

"The infection prevention and control measures are difficult to implement in a ship environment," said Sylvia Briand, WHO's director of global infection. She said that's been the case on many occasions, such as with other infections like norovirus.

"We need to make sure we focus on our public health objective, which is to contain the virus, and not to contain the people," she said. That requires balancing the health risks to people on land with the needs of people onboard the ship.

The WHO's experts said such challenges don't necessitate sweeping bans on cruise ships sailing in Asia.

"We need to reflect on the fact that the vast majority of these cases are within China," said Dr. Michael Ryan, the head of WHO's health emergencies program. "When you look at the population-attack rates within China, even within Hubei and Wuhan, we're talking about an overall attack rate of about 4 per 100,000."

"Outside of Hubei, this epidemic is affecting a very tiny, tiny, tiny proportion of people," he continued. "So if we're going to disrupt every cruise ship in the world on the off chance that there might be some potential contact with some potential pathogen, then where do we stop? Do we shut down the buses around the world? And what happens when other countries are affected — do we take the same measures in that case?"

"We need to be extremely measured with what we do," Ryan said. "And everything we do needs to be based on public health. It needs to be based on evidence. It needs to be based on the principle that there's no such thing as zero risk."