As fears over the virus grow, Mayor de Blasio is encouraging people to work from home and to avoid crowded subway trains. Schools are canceling classes. More New Yorkers are isolating themselves at home.

[The Latest: Read our live coverage of the coronavirus outbreak in the New York Area.]

Yesterday, New Jersey declared a state of emergency. And Governor Cuomo announced that the state’s prisoners are making hand sanitizer.

A top transit official is among the confirmed cases.

Rick Cotton, the executive director of the Port Authority of New York and New Jersey, tested positive for the coronavirus, Mr. Cuomo said yesterday. The Port Authority oversees numerous airports, bridges, tunnels and bus terminals in the New York area, making Mr. Cotton one of the most prominent officials in the United States to contract the virus.

[The head of the Port Authority tested positive for the coronavirus.]

“I’m in self-quarantine at home at the moment,” Mr. Cotton told The Times. His wife, Elizabeth Smith, president of the Central Park Conservancy, also has the virus and is working from home, a spokeswoman for the conservancy said.