An historic day after months of research and clinical trials, the Pfizer-BioNTech Covid vaccine delivery is underway, with millions of doses being distributed across the country. CNBC Senior Health & Science Reporter Meg Tirrell joins Joe Kernen, Becky Quick and Andrew Ross Sorkin with special guest Pfizer CEO, Albert Bourla. Bourla describes the rollout of the life-saving inoculation, reaching dosing goals and combating vaccine hesitancy.