In recent weeks, some hospitals in New York City have begun safeguarding their stockpiles of masks and other protective gear amid suspicions that employees were taking them home.

Administrators at one hospital are allowing pregnant employees to opt out of caring for anyone thought to have the new coronavirus. At another hospital, radiologists have been studying CT scans of coronavirus patients from China.

Although no one in New York has tested positive for the virus, doctors and public health officials in the city and state, amid growing anxiety, have been bracing for the possibility of an epidemic that could strain the health care system.

The pace of the preparations may increase after federal officials urged Americans on Tuesday to prepare for the spread of the virus in the United States, with the possibility that containment strategies could soon give way to mitigation plans.