A top health official at the National Institutes of Health acknowledged that the quarantine aboard the coronavirus-infected Diamond Princess Cruises ship failed while discussing the decision to evacuate hundreds of American passengers – 14 of whom tested positive for the virus.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases at the National Institutes of Health, said the original idea to keep people safely quarantined on the ship wasn't unreasonable. But even with the quarantine process on the ship, virus transmission still occurred.

The Japanese health ministry said Monday that the number of cases confirmed aboard the Diamond Princess had reached 454.

"As it turned out, that was very ineffective in preventing spread on the ship," Fauci told the USA TODAY Editorial Board and reporters Monday. Every hour, another four or five people were being infected.

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The quarantine on the ship was scheduled to end Feb. 19, and those who came back to the U.S. a couple of days ahead of the end of the quarantine probably will have to restart the clock on a new 14-day quarantine.

The Princess Cruises ship was carrying 2,666 guests and 1,045 crew when it set sail and was quarantined after 10 cases of coronavirus were reported Feb. 4. About 380 Americans were on the cruise ship.

"The quarantine process failed," Fauci said. "I'd like to sugarcoat it and try to be diplomatic about it, but it failed. People were getting infected on that ship. Something went awry in the process of the quarantining on that ship. I don't know what it was, but a lot of people got infected on that ship."

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Passengers were instructed to stay in their suites or cabins during the quarantine. Those in interior cabins with no window or outdoor access were able to go on deck for up to an hour and a half but had to stay at least 3 feet from fellow passengers, Matt Smith, a family law attorney from Sacramento, California, told USA TODAY a few days into the quarantine. Meals were dropped off at the door by the ship’s crew.

The crew also distributed masks and thermometers, and passengers were asked to take their temperatures and report readings above 99.5 degrees, Smith said. Common coronavirus symptoms include fever, cough and shortness of breath.

The State Department coordinated with the Department of Health and Human Services and other agencies to bring passengers back to the U.S. It was a tough call to make in the first place, but it grew tougher once 14 passengers tested positive for the virus.

The passengers were thought to be negative and put into the evacuation process. As they were on the bus getting ready to leave, tests came back positive.

Fauci explained there was a choice: Should these people stay in Japan, or should they be flown home?

Passengers ultimately boarded flights home. The infected and the uninfected flew in separate areas of the plane. The infected were in an area Fauci described as similar to a containment laboratory.

To call the situation stressful would be an understatement.

"Many of them were elderly; many of them had underlying conditions," Fauci said. "They just wanted to get home, and we felt it was safe enough on the plane to get them home without infecting anybody else." 

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Fauci said health officials are expecting more positive tests, and he wouldn't be surprised if the number of infected evacuees turned out to be higher than 14.

Not all passengers opted to leave the ship. Smith told USA TODAY he was not planning to take the charter flight back to the U.S. 

"We think the way they are handling this is not safe," Smith said Saturday. "They want to take hundreds of people off the ship before the quarantine here has been completed and without them ever being tested, and they want to throw them on buses together, then a plane, then force them to serve another 14-day quarantine under unknown circumstances."

Contributing: Bill Keveney, Hannah Yasharoff, Morgan Hines, Curtis Tate, Jayme Deerwester and Julia Thompson

This article originally appeared on USA TODAY: Coronavirus: Official explains Diamond Princess cruise quarantine fail