When Americans who were on the cruise ship hit by a hantavirus outbreak arrived back in the United States Monday, most of them were brought to the University of Nebraska Medical Center, which has multiple specialized facilities to monitor and treat people exposed to infectious diseases. 

Fifteen people who were on the cruise are at the National Quarantine Unit on the university's campus in Omaha, Nebraska, officials said Monday. The quarantine unit is the only federally funded facility of its kind and was first used in the early months of the deadly COVID-19 pandemic.

"There is no place in the country that they could be better cared for more safely and more effectively," Dr. Jeffrey Gold, president of the University of Nebraska, said Monday. 

Also at the medical center is the Nebraska Biocontainment Unit, which is used if people in the quarantine unit develop symptoms and need treatment. One of the passengers from the ship was taken there and is doing well, officials said.

Two others from the ship were taken to a biocontainment facility at Emory University in Atlanta. 

Here's what to know about the National Quarantine Unit and Nebraska Biocontainment Unit:

Quarantine unit "more like a hotel"

The quarantine unit is "designed for well individuals who need to be monitored," Angela Hewlett, the medical director of the Nebraska Biocontainment Unit, said Monday. 

There are 20 single-occupancy rooms in the facility. There is no intermingling and no visitors, aside from medical staff, said Michael Wadman, the medical director of National Quarantine Unit. 

While in the unit, individuals are monitored for any symptoms and receive temperature checks.

Each room has "individual negative air pressure systems" and filters to prevent the spread of any possible virus, according to the university. 

The rooms are also designed to keep people comfortable. Hewlett described the facility as "much more like a hotel than a patient care space," noting they don't have hospital equipment. The rooms have their own bathrooms, exercise equipment and Wi-Fi connectivity.

Patient care space in biocontainment unit

If someone in the quarantine unit develops symptoms, they would be assessed and moved to the Nebraska Biocontainment Unit.

"The biocontainment unit is a patient care space," Hewlett said. "That's where we provide hospital-based care to people who need it, and those patients could range from being relatively well and stable to critically ill, requiring multiple procedures and multiple interventions."

Rooms in the biocontainment unit have the same air pressure systems and filters to prevent the spread of viruses. 

"It's a very different facility compared to your routine patient care room in a regular hospital," Hewlett said.

The capacity of the unit varies depending on the virus and how much waste needs to be processed, Hewlett said. 

"We typically can take 10 patients with an airborne disease," such as bird flu and coronaviruses, she said. With the disease caused by hantavirus, which can cause people to "become ill fairly quickly," the unit can typically take two to three patients, she said.

That capacity is why two people were taken to the Emory biocontainment unit, officials said. If more people develop symptoms than the number of beds available at the Nebraska Biocontainment Unit, they could be taken to other treatment centers in the U.S.

History of responding to infectious diseases

Both the UNMC quarantine unit and biocontainment unit have been used for infectious diseases in the past. 

The quarantine unit was first activated in 2020 when Americans were evacuated from China, where the COVID-19 outbreak began. 

The biocontainment unit treated some of the first Americans diagnosed with COVID-19. It was also activated in 2014 to treat Americans with Ebola.

"We are prepared for situations exactly like this," Dr. Michael Ash, the CEO of Nebraska Medicine, said in a statement about the passengers arriving from the hantavirus-stricken cruise ship. "Our teams have trained for decades alongside federal and state partners to make sure we can safely provide care while protecting our staff and the broader community. We are proud to support this national effort."