(CNN) Most of the Americans who were being monitored at the University of Nebraska Medical Center for coronavirus after evacuating a cruise ship in Japan tested positive for the virus, the hospital says.

UNMC said in a statement Thursday that the US Centers for Disease Control and Prevention verified the Nebraska Public Health Lab results showing that 11 of the 13 patients have the novel coronavirus. The other two evacuees who were taken to the Omaha hospital tested negative, the statement said.

Bert Kelly, a CDC spokesman, told CNN that the agency has verified the results, bringing the total of confirmed cases in the United States to 26.

The hospital had said some of the patients had tested positive in Japan but some "came with a lack of clarity of what their test results were," Shelly Schwedhelm told CNN. Schwedhelm is the UNMC/Nebraska Medical Executive Director of Emergency Management and Biopreparedness who has clinical oversight of the quarantine and biocontainment units.

Nine of the patients had tested positive for the virus in Japan and were positive again after being rested in the United States, another CDC spokesman, Joe Smith, told CNN on Friday.

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