Hot off the presses, CDC guidance for businesses.
This is the latest and greatest from the Centers for Disease Control and Prevention (CDC). They note that we very early in the new coronavirus 2019-nCoV. Therefore, more information will likely be forthcoming as more is known about the disease and its transmission. Thus, you see the "interim" in the title of the guidance.
For now, this is good guidance for employers and businesses: CDC — Interim Guidance for Businesses and Employers to Plan and Respond to 2019 Novel Coronavirus (2019-nCoV), February 2020.