In the years after the Sept. 11 attacks, officials at Nebraska Medical Center envisioned a time when the nation would need a large, secure treatment center to guard against the threats of bioterrorism and infectious diseases. They spent $1 million to transform an empty wing of the hospital into a 10-bed biocontainment unit, complete with concrete walls, filtered air and video links to the nursing station.

Then they waited.

The beds sat empty for years, until an Ebola outbreak in 2014. The unit became a central player in treating Americans returning from West Africa with the lethal disease. Nurses wearing face shields, water-resistant gowns and three pairs of surgical gloves treated three Ebola patients. When that threat subsided, the unit returned to being a quiet ward used only for training and planning.

Now, the hospital in Omaha, Nebraska is once again playing a key role in an international health emergency, after 13 Americans who tested positive for or were exposed to the new coronavirus on a contaminated cruise ship in Japan were hustled off an international flight and transported there for evaluation Monday.

In addition to the biocontainment unit, the hospital’s campus has the only federal quarantine unit in the country.

“We do a huge amount of research in these areas,” said Dr. Jeffrey P. Gold, chancellor of the University of Nebraska Medical Center, citing work on infectious diseases and research on countermeasures to weapons of mass destruction.

“What — heaven forbid — happens if an employee or staff member gets exposed to one of these agents, or even worse than that, gets infected, where are you going to put them? You can’t just call up a local hospital and say, ‘I’ve got somebody who has anthrax, make up a bed,’” he said. “You need facilities that can do everything from air and water handling to the complexities of waste disposal.”

By Tuesday, hospital officials said they were awaiting additional test results but anticipated that most of the people in the group of 13 would be confirmed as having the coronavirus, the latest development in a sprawling international outbreak which originated in Wuhan, China. The virus has sickened tens of thousands of people in at least two dozen countries.

Still, the risk of infection outside of China remains low, and the virus is considered a less immediate threat than the seasonal flu.

Before arriving in Omaha, the 13 patients — all adults — had been stuck for days aboard a cruise ship in Yokohama, Japan, where Japanese officials have confirmed more than 400 cases of the virus. As officials prepared to evacuate Americans on board, the U.S. Embassy in Tokyo told passengers that no one infected with the coronavirus would be allowed to board flights to the United States. But during a chaotic evacuation Monday, the decision was apparently reversed at the last minute.

Officials have said that 14 infected evacuees were allowed to board the planes, which flew to military bases in California and Texas. Many of the infected evacuees then continued on for evaluation in Omaha, along with some of their spouses.

The groups landed in Omaha on Monday morning and traveled in passenger buses to the hospital, along with a police escort.

The evacuees who arrived were upbeat — if a bit cold, because of the weather in Nebraska — and glad to have a few moments of fresh air as they stepped off the plane, said Mike Wadman, a medical director for the National Quarantine Unit. He said some of them had been in interior rooms of the cruise ship and had not been outside for many days.

At least two of the more seriously ill evacuees were being monitored in the hospital’s biocontainment unit, a special ward on the seventh floor where the three Ebola patients were treated in 2014. It looks like a typical hospital ward but is equipped with special technology, including doors that act like an airlock and a separate area for doctors and nurses to change and shower.

The other evacuees are being housed across the street in a 20-bed quarantine unit, which opened last year and is a joint venture with the University of Nebraska Medical Center. The rooms resemble something out of a college dorm: beige walls, a single bed, wooden furniture. But each room also comes with exercise equipment, like a stationary bike or a treadmill, to help patients stay active if they are feeling well enough. Patients will stay in quarantine for 14 days if they continue to test negative and as long as necessary if they have the virus.

Officials plan to provide books and games to those who want them, similar to what they have done with a group of 57 people who are separately being quarantined at a National Guard facility outside Omaha after flying back from Wuhan. Taylor Wilson, a spokesman for Nebraska Medicine, said patients there have sent in requests for entertainment, including a guitar, which was granted, and a game of Twister, which he said was turned down because “it’s probably not the best quarantine activity.”

To fight against isolation, patients in the biocontainment rooms also have access to video technology that attaches to a separate room, so they can virtually visit with loved ones without risk of infection, Gold said.

“I remember when we had Ebola patients, their families used to come, and they used to read stories to their children; they would pray with their wife,” he said. “It was quite emotional.”