CNBC.com's MacKenzie Sigalos brings you the day's top business news headlines. On today's show, Dr. Kathleen Neuzil from the University of Maryland School of Medicine breaks down the next steps and challenges involved in getting Pfizer's 90% effective vaccine to the broader American population. Plus, after Monday's raucous trading session, CNBC's Kate Rooney dives into which investors were buying the dip in "stay at home" stocks like Zoom and Peloton.