Dr. Anthony Fauci to Sen. Rand Paul at hearing: You do not know what you're talking about

Senator Rand Paul (R-Ky.) and Dr. Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, got into a heated exchange this morning during a hearing on the origins of the Covid-19 virus. After Paul alleged that Fauci lied to Congress, the doctor told Paul he didn't know what he was talking about. For access to live and exclusive video from CNBC subscribe to CNBC PRO: White House chief medical advisor Dr. Anthony Fauci and Sen. Rand Paul traded barbs in a heated exchange at a Senate hearing Tuesday over whether the National Institutes of Health funded controversial research Paul claims could have contributed to the Covid-19 pandemic. Paul grilled Fauci about an NIH funded study that he says qualifies as gain-of-function research, the process of altering a pathogen to make it more transmissible in order to better predict emerging diseases. Fauci previously denied in previous Senate testimony that the NIH has directly funded the research