The Food and Drug Administration first has to approve the test for wider distribution, the C.D.C. said. The United States has 11 confirmed cases so far.

Dr. Nancy Messonnier, director of the National Center for Immunization and Respiratory Diseases, said that 167 “patients under investigation” who had symptoms like cough or fever, and had traveled to Wuhan or been in contact with a patient, had negative test results. A further 82 tests are pending, including some with samples in transit to the agency’s labs.

The severity of the disease has varied in patients in the United States, Dr. Messonnier said. Some have had mild illness, but a few have been more severely ill, with some needing oxygen. None has died.

Of the 11 patients, nine had been to Wuhan and two were close contacts of patients who had traveled, indicating that person-to-person spread of the virus has occurred in the United States. “We expect to find additional cases in the United States and we expect more cases of person-to-person spread among close contacts,” Dr. Messonnier said.

With the C.D.C. already running through its allocations for emergency response funds, the Department of Health and Human Services has formally informed Congress that it may transfer up to $136 million to help combat the spread of coronavirus, according to a person with knowledge of the notification.

Of the maximum $136 million that the department may transfer, up to $75 million would go to the disease centers, up to $52 million to the department’s Office of the Assistant Secretary for Preparedness and Response, and up to $8 million to the department’s Office of Global Affairs. It was unclear where that money would be transferred from.

The State Department plans to repatriate more people from Wuhan, and the C.D.C. has sent four teams to military locations where their flights will land, Dr. Messonnier said. She said she did not know yet how many passengers would be returning.