Roger Seheult, MD of MedCram explains how “natural immunity” (from a previous COVID-19 infection) compares with vaccines (Pfizer, Moderna, AstraZeneca) VS. the Delta coronavirus variant. (This video was recorded on July 24, 2021). Roger Seheult, MD is the co-founder and lead professor at https://www.medcram.com He is Board Certified in Internal Medicine, Pulmonary Disease, Critical Care, and Sleep Medicine and an Associate Professor at the University of California, Riverside School of Medicine.