Why Herd Immunity Is Slipping Away

From the earliest days of the pandemic, herd immunity has consistently factored into conversations about how countries can find their way out of lockdowns and restrictions. Now, many experts believe that the United States may never reach the requisite level of immunity. We explore why, and what it might look like to live in a country where there is no herd immunity against the coronavirus. Guest: Apoorva Mandavilli, a science and global health reporter for The New York Times.