Dr. Larry Brilliant, the acclaimed epidemiologist and philanthropist who helped to end smallpox, tells Ian Bremmer he is confident there will be a vaccine for COVID-19 in 12-18 months. In an interview for the latest episode of GZERO World, Dr. Brilliant breaks down the steps it will take to get to herd immunity and safely reopen the global economy, and what we can expect to see scientifically over the next year.