An American doctor who helped care for passengers on a cruise ship stricken by hantavirus has been cleared to leave a high-security isolation unit.

Stephen Kornfeld was among more than 120 people evacuated from the ship. He was placed in the Nebraska Biocontainment Unit after a nasal swab yielded unclear results.

“I feel wonderful, 100%,” Kornfeld told CNN before being cleared. He will now join 15 other Americans under observation at the National Quarantine Unit.

Health officials say the international evacuation and quarantine operation was a success. The World Health Organization reports 11 cases linked to the outbreak, including eight confirmed and three deaths.