With its first confirmed case of the coronavirus, New York City has shifted from trepidation to high alert. Governor Cuomo said yesterday that it was “inevitable” the outbreak would spread. Both the governor and Mayor de Blasio have urged calm, noting that the virus produces only mild symptoms in many people. [Coronavirus in New York: “Community spread is going to be real,” Governor Cuomo said. ] Still, the arrival of the coronavirus has rapidly raised anxiety levels among New Yorkers, who spend their days in close quarters in office and residential buildings, on crowded sidewalks and in packed subway cars.