When will the coronavirus vaccine be ready? Epidemiologist Seth Berkley (head of Gavi, the Vaccine Alliance) takes us inside the effort to create a vaccine for COVID-19. With clarity and urgency, he explains what makes it so challenging to develop, when we can expect it to be rolled out at scale and why we'll need global collaboration to get it done. (This virtual conversation is part of the TED Connects series, hosted by head of TED Chris Anderson and current affairs curator Whitney Pennington Rodgers. Recorded March 26, 2020)