OMAHA, Neb. (AP) — Five of the 18 American cruise ship passengers who have been staying at a national quarantine facility in Nebraska after being exposed to hantavirus are going home, U.S. health officials said Monday.

The five people will complete their monitoring at home after remaining symptom-free and meeting criteria for monitoring outside the quarantine unit at the University of Nebraska Medical Center.

They are leaving Omaha about three weeks after they and the 13 other Americans arrived in Nebraska following a deadly outbreak of hantavirus on a cruise ship traveling in the South Atlantic Ocean.

Hantaviruses usually spread when people inhale contaminated residue of rodent droppings, but the hantavirus that has caused the current outbreak, called the Andes virus, may be able to spread between people in rare cases.

A total of 13 confirmed or probable hantavirus cases, including three deaths, have been linked to the ship, according to the World Health Organization.

No Andes virus cases have been confirmed in the U.S., and the risk to the public remains low, health officials said.

None of the U.S. passengers has shown any symptoms, a spokesperson for Nebraska Medicine said Monday.

Symptoms of hantavirus have taken as long as 42 days to appear in previous outbreaks, but some medical experts say most people who develop symptoms do so within 21 days.

The doctors in Omaha monitoring the passengers had said previously that they would work with each person individually to determine if it was appropriate for them to go home to finish their recommended 42-day quarantine period.

Federal officials arranged travel for the five people going home, in coordination with state and local authorities. Officials said the travel was not to be on commercial flights, with appropriate biocontainment measures in place. State health departments will continue daily symptom monitoring, maintain 24/7 oversight and provide guidance.

Two of the people returning to their homes live outside New York City, said city Health Commissioner Dr. Alister Martin.

One of the remaining passengers, Jake Rosmarin, posted on his blog Sunday that he plans to stay at the Omaha unit for his final three weeks of quarantine because he would have immediate access to care if he gets sick and he doesn’t want to risk unnecessarily exposing anyone else.

Rosmarin, who posts daily updates about his experience, said he’s not judging anyone who decided to go home.

“For me personally, this experience has been incredibly traumatic,” Rosmarin said. “I don’t think I’ve fully processed everything yet, and right now I don’t want to leave until I know there is no risk of me getting sick or putting my family, friends, or the general public at risk.”

Not everyone quarantined in Nebraska has been happy about it. About a week after the 18 arrived, U.S. health officials issued quarantine orders forcing two passengers who wanted to leave to stay there.

Stobbe reported from New York.

The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education and the Robert Wood Johnson Foundation. The AP is solely responsible for all content.