The Centers for Disease Control and Prevention and Illinois public health officials confirmed Thursday the nation’s first person-to-person transmission of the coronavirus that has already killed at least 171 people in China and infected more than 8,200 since emerging less than a month ago.

The new patient is the spouse of the Chicago woman who brought the infection back from Wuhan, China, the epicenter of the outbreak, CDC and Illinois health officials said during a press briefing. Public health officials are also monitoring 21 patients in Illinois for possible infections.