DOVER, Del. (AP) — A University of Delaware professor has tested positive for the coronavirus, prompting the school on Wednesday to cancel classes, move up spring break and announce that all instruction will take place online when the semester resumes.

The unidentified professor, who is over the age of 50, was exposed to a confirmed coronavirus case in another state and self-isolated at home as soon as symptoms appeared, officials said. Public health director Dr. Karyl Rattay said the man is not severely ill and is doing well.

Epidemiologists from the Division of Public Health are working to identify any close contacts of the individuals who were possibly exposed, officials said.

With university president Dennis Assanis looking on, Gov. John Carney said at a news conference that state officials have been preparing for the virus for weeks, and that they are ready to respond.

"We're taking this extremely seriously ... but we are not panicking, and neither should you," Carney said.

For most people, the virus causes only mild or moderate symptoms such as fever and cough. For some, especially the elderly and people with existing health problems, it can cause more severe illness, including pneumonia. People with mild illness recover in about two weeks, while those with more severe illness may take three to six weeks to recover.

Nevertheless, concern about the virus spreading in the U.S. has prompted a growing number of bans on large public gatherings, and several universities around the country are moving classes online.

Officials at the University of Delaware, which has more than 18,000 undergraduates at its Newark campus, said classes would be conducted online for the rest of the semester, or until further notice. They also suspended classes Thursday and Friday and said spring break would be moved up to Saturday.

Classes are scheduled to resume in an online format on March 23. Officials said students who choose to leave campus for the break should take any personal and academic materials they might need to complete the semester online.

University officials already had canceled this year's UDance, a popular dance marathon that raises money for childhood cancer research and was to have been held March 22. The university also has suspended all programming for its Osher Lifelong Learning Institute until further notice. The institute serves those 50 and older, a population that includes those most vulnerable to serious complications from the virus.

University-sponsored travel to all international locations has been banned through the end of the spring semester. The school also is discouraging personal international travel, including during spring break.

Carney canceled a town hall meeting that had been scheduled for Wednesday evening at the Newark Senior Center and opted instead for an online "virtual town hall" with state Health and Social Services Secretary Dr. Kara Odom Walker. Carney's office said the decision was made "out of an abundance of caution."

At the State Capitol, lawmakers have not ruled out postponing the legislative session if circumstances merit. Members of the General Assembly have been on break for several weeks during budget committee hearings but are scheduled to resume the session on Tuesday.