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.

Two patients whose disease status was unclear when they arrived at UNMC tested positive when they were retested. Two patients were confirmed negative in both tests, Smith said.

“We wanted to be certain of what we had, and today we know that we have 11 positives,” he said.

UNMC said several people are exhibiting minor symptoms but others are not showing any symptoms.

The US Office of the Assistant Secretary for Preparedness Response asked UNMC early Monday to take in 13 patients who had either tested positive, or had a high likelihood of testing positive, for the novel coronavirus.

The patients had been on a cruise ship docked off the cost of Japan for two weeks.

UNMC was commissioned by the CDC in 2005 to create the biocontainment unit where three patients currently are. The rest of the patients are in a separate federal quarantine center on the campus that UNMC built through a private-public partnership.

In 2014, UNMC successfully treated three patients with Ebola, and the medical facility has the capacity to manage other highly infectious diseases such as SARS, monkeypox and multidrug-resistant tuberculosis.

CORRECTION: A prior version of this story used an incorrect acronym for the University of Nebraska Medical Center, or UNMC.

CNN’s Jen Christensen contributed to this report.