Karen DeSalvo, the chief health officer at Google, explains the partnership between big tech and public health in slowing the spread of COVID-19 -- and discusses a new contact tracing technology recently rolled out by Google and Apple that aims to ease the burden on health workers and provide scientists critical time to create a vaccine. (This virtual conversation, hosted by current affairs curator Whitney Pennington Rodgers and head of TED Chris Anderson, was recorded on May 27, 2020.)