CNBC's Meg Tirrell explains how the coronavirus vaccine data monitoring process works

U.S pharmaceutical giant Pfizer and German biotech firm BioNTech said their coronavirus vaccine was more than 90% effective in preventing Covid-19 among those without evidence of prior infection, according to data published Monday from their late-stage vaccine trial. CNBC's Meg Tirrell reports the latest on the news.
Mon, Nov 9 202010:27 AM EST