Dr. Stephen Kornfeld, a passenger from the MV Hondius cruise ship who had tested “faintly positive” for hantavirus, has now tested negative and been moved out of a Nebraska biocontainment unit.

Kornfeld, 69, an Oregon oncologist, had helped care for ill passengers aboard the cruise ship and himself developed a “flu-like illness,” he told CNN’s Erin Burnett on Tuesday.

“At the time, it was felt like this is just some virus,” he said. “And now, in retrospect, there is a question, could it have been hantavirus? But it’s just speculation. There’s no way to really know.”

His initial hantavirus test results — from tests taken before he returned to the US — landed him in the biocontainment unit at the University of Nebraska Medical Center. He told Burnett on Wednesday that confirmatory PCR testing was negative. The results of blood tests are still pending.

Kornfeld is now in the quarantine unit with 15 other American passengers from the ship. None of the 16 is currently reporting symptoms of illness. Two other passengers are being monitored at Emory University in Atlanta.

The World Health Organization said in an update earlier Wednesday that the current hantavirus case count tied to the Hondius stood at 11, but Kornfeld’s initial positive test was among that number.

US officials have said Hondius passengers may be able to return home to complete weeks of health monitoring for Andes hantavirus. However, the American passengers who are in quarantine in Nebraska are “encouraged to stay” at the facility for monitoring, officials with the US Centers for Disease Control and Prevention said Wednesday. Federal officials are working with medical staff to “ensure that they have the appropriate disposition,” the CDC officials said in the agency’s first briefing since the hantavirus outbreak began.

“Our goal is to continue to work with them for the best possible place for them,” said Dr. David Fitter, incident manager for the CDC’s hantavirus response.

Hantavirus has a long incubation period, and people with high-risk exposures — including cruise ship passengers and people who were on an international flight with a sick passenger — should be monitored for 42 days, health officials say.

Some countries are testing all of their passengers who were exposed to hantavirus. But the “CDC currently recommends testing only for people with symptoms,” Fitter said.

The risk to the general public remains low, WHO and CDC say. At least 19 other people across at least 10 states also may have been exposed to hantavirus, and they are being encouraged to isolate at home as the CDC works with state and local partners to help monitor them. But “currently, there are no state or federal quarantine orders that have been drawn,” Fitter said. (CNN)

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