Doctor on COVID-19 variants spreading rapidly in U.S.
More contagious COVID-19 variants are spreading rapidly in the U.S. and a new study by the CDC finds the strain first found in the U.K. will become dominant here by March. Dr. Ron Elfenbein joins CBSN to discuss that plus President Biden's recent comments on the pandemic made in an exclusive interview with CBS News' Norah O'Donnell.