“All the hospitals are taxed with a large flu season and other bugs,” said Dr. Mark Jarrett, the chief quality officer for Northwell Health, which operates 23 hospitals across Long Island and elsewhere in New York. About 400 patients are coming to its emergency rooms each day with flulike symptoms.

“Everybody is at maximum capacity,” Dr. Jarrett said.

Northwell activated its emergency operations center earlier this month in response to concerns that the virus, now in epidemic proportions across China, could become a pandemic, similar to the hospital system’s reaction to the threat of swine flu in 2009 and Ebola in 2014.

Although the Trump administration declared a public health emergency for coronavirus late last week, Dr. Robert Redfield, the head of the Centers for Disease Control and Prevention, stressed on Friday at a news briefing that the risk for Americans was still low. Hundreds of people who returned to the United States from Wuhan have been quarantined at military bases, and others possibly exposed have been asked to self-quarantine or stay at home.

But Dr. Redfield also said that officials were beginning to actively discuss what other steps would have to be taken in the event that the new coronavirus spread in this country. Asked about emergency funding, Alex M. Azar II, the secretary for health and human services, said he did not believe agencies required additional funds right now.

Still, across the country, hospitals are taking steps to prepare for the potential threat.

Some are already scrambling to find sufficient supplies of medical face masks, especially so-called N95 respirators, which are more effective for preventing infection. Manufacturers are struggling to keep up with global demand and the desperate need for supplies in China.