First, we sift through the week's news, with some disappointing Covid-19 vaccine data, a pair of setbacks for biotech, and the Wall Street debut of 23andMe. Then, vaccinologist Paul Offit joins us to explain the scientific debate over whether we'll need booster vaccine doses to stay protected from SARS-CoV-2. Finally, Truist Securities analyst Robyn Karnauskas calls in to talk about her bold 2020 prediction that Biogen's controversial treatment for Alzheimer's disease would eventually win FDA approval.