An American who was exposed to the new coronavirus on a Japanese cruise ship and who was being monitored at an Omaha hospital has been released from quarantine.

The University of Nebraska Medical Center said in a statement Tuesday that the patient tested negative for COVID-19 three times and was cleared to leave quarantine. Seven others who were exposed to the virus on the Diamond Princess were released from quarantine in Omaha last week.

For most people, the new coronavirus causes only mild or moderate symptoms, such as fever and cough. For some, especially older adults and people with existing health problems, it can cause more severe illness, including pneumonia.

The vast majority of people recover from the new virus. According to the World Health Organization, people with mild illness recover in about two weeks, while those with more severe illness may take three to six weeks to recover. In mainland China, where the virus first exploded, more than 80,000 people have been diagnosed and more than 58,000 have so far recovered.

Seven other passengers who were evacuated from the ship last month have tested positive for COVID-19, and they remain at the Omaha hospital. One of them was being treated in the hospital's Nebraska Biocontainment Unit and was in good condition Tuesday. The other six remain in the hospital's National Quarantine Unit.

In addition to the cruise ship passengers, a 36-year-old Omaha woman who contracted COVID-19 while travelling to the United Kingdom remains in critical condition Tuesday in the Nebraska Biocontainment Unit, the hospital said. Her father and another family member also tested positive for COVID-19, but they are recovering at home.

The father told  the Omaha World-Herald that his family has been subjected to social media accusations that they had knowingly spreading the virus.

"We had absolutely no idea," he told the newspaper. "It definitely didn't pop into my mind that she had coronavirus."

The World-Herald did not name the father or his daughter to protect their privacy and to stanch the flow of criticism directed at them.

The virus has sickened around 116,000 people worldwide with over 4,000 deaths.