What are coronavirus vaccine clinical trials designed to show, and what they are not designed to show? Dr. Bruce Gellin of the Sabin Vaccine Institute joined Corinne Cardina and Olivia Zitkus of Fool.com’s Healthcare and Cannabis Bureau on a Dec. 18 episode of Fool Live, where he discussed vaccine safety and efficacy, and why it will take some time for us to understand how well new vaccines from Moderna (NASDAQ: MRNA) and the Pfizer (NYSE: PFE)–BioNTech (NASDAQ: BNTX) team curb the spread of the coronavirus.