BOSTON (AP) — The number of people in Massachusetts who have tested positive for the new coronavirus jumped to 41 on Monday, state public health officials said, leading Boston to cancel its annual St. Patrick's Day Parade and Amherst College to move classes online.

Of the 41 confirmed or presumptive positive cases — up from the 28 reported Sunday — 32 are associated with a Biogen employee meeting held in late February at a Boston hotel. The cases are either employees or close contacts of employees.

State Department of Public Health officials said that all of the new presumptive positive cases are in isolation at home or are in a health care setting. Of the 41 cases, four individuals have been hospitalized.

Boston Mayor Marty Walsh announced late Monday that the city decided to cancel the parade as a precautionary measure.

Amherst College released a statement saying that all classes will be moved online after spring break, beginning March 23. The college also canceled classes for Thursday and Friday so faculty and staff have time to work on alternate modes of delivering courses.

There remains one confirmed case in Massachusetts. The other cases are considered presumptive until confirmed by the federal Centers for Disease Control and Prevention.

In addition to those cases associated with the Biogen conference, four cases are considered travel-related and five are under investigation.

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.

Walsh said the decision to cancel the parade was made “out of an abundance of caution to ensure that we are doing what is needed to keep the residents of Boston safe and healthy.”

“While the risk in Boston remains low, this situation is changing very quickly and we are closely monitoring any local cases," Walsh said in a statement. “Our top priority is preventing any new cases, to the best of our ability.”

The state's insurance commissioner has said the cost of testing and treatment for the coronavirus will be covered by health insurers in Massachusetts.

COVID-19 has flu-like symptoms ranging from mild to severe, including fever, cough and shortness of breath. The CDC advises those who are mildly ill with the virus to stay home and avoid public areas to avoid spreading it.

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