Housing and Urban Development Secretary Ben Carson tested positive for COVID-19 on Monday after attending a White House election night party last week. Mark Meadows, who also attended that party, tested positive last week. The man leading President Trump's post-election legal fight, attorney David Bossie, also revealed his positive diagnosis Monday. Dr. Dara Kass, an emergency room physician and a member of the group Doctors for Biden, spoke to CBSN's "Red & Blue" host Elaine Quijano about the promising news from Pfizer's vaccine trial and the crucial period the U.S. is entering in its efforts to contain the virus.