Contact tracing -- the process of identifying people who may have been exposed to the coronavirus in order to slow its spread -- is a fundamental tool in the fight against COVID-19. How can we scale this critical work across the entire United States? Joia Mukherjee, chief medical officer of Partners in Health, discusses how her team is working with public health agencies to ramp up contact tracing for the country's most vulnerable communities -- and shows why it will take a compassionate approach to be truly effective. (This ambitious plan is part of The Audacious Project, TED's initiative to inspire and fund global change. The conversation, hosted by head of TED Chris Anderson and current affairs curator Whitney Pennington Rodgers, was recorded May 27, 2020.)