Related Program: Morning Edition Herd Immunity Is At Risk If Many People In U.S. Say 'No' To Vaccine By Geoff Brumfiel • Apr 7, 2021 Related Program: Morning Edition ShareTweetEmail Listen Listening... / Originally published on April 7, 2021 8:14 am Copyright 2021 NPR. To see more, visit https://www.npr.org. ShareTweetEmail