New York City health officials announced on Saturday that a patient at Bellevue Hospital Center might have the new coronavirus and that samples were being sent to the federal authorities for laboratory testing. If confirmed, it would be the first known instance of the virus in New York City.

Based on the patient’s symptoms and travel history from China, city officials were taking the potential case seriously. This was the first time city officials had sent a sample to the Centers for Disease Control and Prevention for testing.

Another reason the health authorities suspect it might be the new coronavirus: They had tested the patient for influenza and other common illnesses, and those tests came back negative, health officials said.

They said they did not expect to receive results from the C.D.C. for 36 to 48 hours, or possibly longer.