American doctor being treated for Ebola in Atlanta; second American expected to arrive Tuesday

On Monday evening, Dr. Sanjay Gupta joined Erin Burnett for a live interview, during which he reported on the experimental serum administered to the first U.S. Ebola patients.

Four days ago, with his conditions worsening, American Kent Brantly, was injected with ZMapp. Within an hour of receiving the experimental medication, he appeared to make a dramatic turnaround.

On Saturday, Brantly arrived in Atlanta, even walking from the ambulance to Emory University Hospital where he is being treated under extreme caution.

Watch the above clip for more of Gupta's medical insight, including an update on Brantly's colleague, Nancy Writebol, who was also infected with Ebola and received the ZMapp serum.