As of February 4, more than 20,000 cases of infections had been reported, with 98.9% of the cases in China, and the virus had been tied to more than 400 deaths.

As of February 4, the number of 2019-nCoV cases is estimated at 20,701, with 427 deaths and 727 patients considered recovered, according to a dashboard created by the Center for Systems Science and Engineering at Johns Hopkins University.

The CDC confirmed that 2019-nCoV has spread between two people in the U.S. The latest patient is an Illinois resident with no history of travel to Wuhan, but shared a household with a patient diagnosed with the virus on January 21.

The new virus has been compared to MERS-CoV and SARS-CoV. The CDC says the process for evaluation and the PUI form to report suspected cases remains unchanged from the ones used with MERS-CoV, which was the virus of concern in 2015.