On January 31, 2020 Health and Human Services Secretary declared a public health emergency for the entire United States to aid the nation’s healthcare community in responding to 2019 novel coronavirus. Following that announcement, DHS and TSA announced that effective Sunday Feb 2 at 5 pm. the US will be barring entry of foreign nationals to US and subjecting US Citizens to 14 day quarantine if they have traveled to mainland China in 14 days preceding request for admission.
Specifically, US Citizens who have traveled to Hubei province will be subject to 14 days mandatory quarantine and U.S. citizens who have been in other areas of mainland China within 14 days of their return will undergo proactive entry health screening and up to 14 days of self-quarantine with health monitoring to ensure they have not contracted the virus and do not pose a public health risk. Generally, foreign nationals (other than immediate family of U.S. citizens, permanent residents, and flight crew) who have traveled in China within 14 days of their arrival, will be denied entry into the United States.
See HHS Announcement
See DHS announcement
See article re TSA Directives