(WBBM NEWSRADIO) -- The U.S. has declared a public health emergency on coronavirus, restricting the entry of some people.
Here in Illinois, the number of cases remains at 2: a husband and wife from Chicago.
Now, NBC News is reporting the family's infant grandson has developed a fever and is being tested for the virus.
“Contact tracing” is something that public health officials do every day, and Dr. Allison Arwady, commissioner of the Chicago Department of Public Health, explains how it works with coronavirus.
"We make a big list of all the people who may have been contact with our confirmed case during the time they could potentially have been spreading disease. And then we work to trace every one of these folks and to follow up with them every day to see if they are developing symptoms."
Dr. Arwady said Friday a contact is someone who has had at least 10 minutes of interaction within six feet.
She would not say how many people are on the "big list" in the case of the Chicago couple.
There is no need to cancel mass gatherings, she said.