Slideshow ( 5 images )

(Reuters) - Five people in the United States, all of whom recently traveled from Wuhan, China, have been diagnosed with the new coronavirus, officials of the federal Centers for Disease Control and Prevention said on Sunday.

The count includes new patients identified over the weekend in the Los Angeles and Phoenix areas, as well as cases reported earlier in Chicago and Seattle.

Another 25 people have tested negative for the illness, but at least 100 more possible cases are being investigated, Nancy Messonnier, director of the CDC’s National Center for Immunization and Respiratory Diseases, said in a conference call with reporters.

She said to expect more cases to be reported in the United States in coming days.

Messonnier described the risk to health in the United States as “low at this time” because all of the patients traveled from Wuhan. She said there is no evidence in the United States of the disease spreading to other people.

Health authorities around the world are racing to prevent a pandemic after more than 2,000 people were infected in China and 56 have died after contracting the virus.

The newly identified coronavirus has created alarm because there are a still many important unknowns surrounding it. It can cause pneumonia, which has been deadly in some cases. It is still too early to know just how dangerous it is and how easily it spreads between people.