Mayor of the District of Columbia Muriel Bowser (D) talks to Meet the Press about the security preparations in Washington, DC ahead of Joe Biden's inauguration. Sen. Cory Booker (D-N.J.) discusses the next phase of the impeachment process as President Trump's administration comes to an end. Rep. Nancy Mace (R-S.C.) tells Chuck Todd that she opposed impeachment because Democrats skipped the usual investigative process.  Dr. Anthony Fauci discusses the more virulent coronavirus strains that are under study, and the future of vaccination efforts. Kristen Welker, Rich Lowry and Former Sen. Claire McCaskill (D-Mo.) join the Meet the Press roundtable.