During his public noontime prayer Sunday in St. Peter's Square, Pope Leo thanked residents of the Canary Islands for their "hospitality" shown to the MV Hondius and its passengers.

"I would like to thank the people of the Canary Islands who, with the hospitality characteristic of them, welcomed the cruise ship Hondius and the passengers infected with the hantavirus," the pontiff said.

"I look forward to seeing all of you next month during my visit to the islands," the pope added, referring to the visit that had already been planned as part of a broader trip to Spain in June.

The passengers aboard the MV Hondius, including 17 Americans, disembarked from the ship Sunday in Tenerife, in the Canary Islands, to begin their journeys back to their home countries.

-ABC News' Phoebe Natanson

The hantavirus outbreak aboard the MV Hondius "is on the end of its run right now," a top infectious disease expert told ABC News "This Week" Sunday.

"The good news is that, in a sense, it is hantavirus and not another coronavirus or influenza virus. This is one that has very limited ability to be transmitted person to person. In fact, it's a rare exception," Dr. Michael Osterholm, director of the University of Minnesota's Center for Infectious Disease Research and Policy (CIDRAP), told ABC News' Martha Raddatz. "And so we have no question about the fact that this really is on the end of its run right now."

There are about 30 cases of hantavirus a year in the U.S. on average, and "they mostly occur west of the Mississippi" – about 96%, Osterholm said, due to a specific mouse that lives in that region. He also said that person-to-person transmission of the hantavirus strain in question is "a very rare exception," and only occurs when someone is exhibiting symptoms of the virus.

"Right now, you can manage the individuals who have been exposed very simply by asking them twice a day, 'are you experiencing any kind of a fever?' And then take the temperature: 'Do you have any symptoms?' If somebody is identified right at that point, you can put basically an N95 mask on and stop all transmission," Osterholm said.

"So this is why we don't need this high-tech, you know, containment facilities, et cetera, to monitor these people. We can monitor them very simply," Osterholm added, explaining why quarantining returning Americans isn't necessary.

"I have complete confidence that we will have good compliance here," Osterholm said of monitoring passengers who are returning. "And I think within days, this will no longer be a story."

-ABC News' Quinn Scanlan

An airplane from the U.S. is expected to land in Tenerife, in the Canary Island, at 5:23 p.m. local time/12:23 p.m. Eastern time, according to a source in the Spanish president's office.

The aircraft will carry U.S. passengers only, according to the source. There are 17 U.S. citizens aboard the ship who will be returning to the United States.

As of now, the U.S. airplane is expected to take off from Tenerife at 9:30 p.m. local time/4:30 p.m. Eastern time but could possibly depart earlier if circumstances allow, the source said.

The passengers onboard the MV Hondius began disembarking from the ship in Tenerife on Sunday morning.

-ABC News' Aicha El Hammar

"The average person has no reason to worry" about potential hantavirus infection, according to an expert with the World Health Organization (WHO).

"This Andes hantavirus has spread in limited amount from human to human ... This is not COVID, this is not passing someone in a hallway in an airport outside at a stadium and getting infected," Dr. Boris Pavlin, an epidemiologist and the team lead for Field and Humanitarian Epidemiology at the WHO, told ABC News.

He also said the investigation in the hantavirus infection cluster's origin indicates "there's absolutely every reason to believe that this came from rodents" and that it did not originate from the region the ship departed, but elsewhere in northern Argentina and Chile, where the long-tailed rice rat, which is the specific carrier of the Andes hantavirus strain, is common. Pavlin also confirmed that the first hantavirus cases on board the MV Hondius had previously traveled to this region in the north.

Pavlin additionally confirmed that no one on board was currently showing any symptoms but were "just being monitored as a precautionary measure." He also said he understands why people are concerned.

"I know it's a new name for a lot of people, but this is not a new virus. We've known about it for decades and it's not surprising us," Pavlin said.

-ABC News' Maggie Rulli, Dragana Jovanovic and Aicha El Hammar