Pfizer is saying that their early data shows its COVID-19 vaccine is 90% effective. Infectious disease expert Dr. William Haseltine joins Stephanie Ruhle to discuss his reaction to this news and what he thinks American citizens still need to do to fight the virus. Aired on 11/09/2020. » Subscribe to MSNBC: http://on.msnbc.com/SubscribeTomsnbc MSNBC delivers breaking news, in-depth analysis of politics headlines, as well as commentary and informed perspectives. Find video clips and segments from The Rachel Maddow Show, Morning Joe, Meet the Press Daily, The Beat with Ari Melber, Deadline: White House with Nicolle Wallace, Hardball, All In, Last Word, 11th Hour, and more. Connect with MSNBC Online Visit msnbc.com: http://on.msnbc.com/Readmsnbc Subscribe to MSNBC Newsletter: http://MSNBC.com/NewslettersYouTube Find MSNBC on Facebook: http://on.msnbc.com/Likemsnbc Follow MSNBC on Twitter: http://on.msnbc.com/Followmsnbc Follow MSNBC on Instagram: http://on.msnbc.com/Instamsnbc #WilliamHaseltine #PfizerVaccine #MSNBC Dr. William: Virus Is ‘Very Serious’ Despite Successful Pfizer Vaccine Trial | Stephanie Ruhle