The country's top infectious disease expert, Dr. Anthony Fauci, joins Ian Bremmer to talk vaccines, school re-openings, and when—and how—the pandemic could finally come end. He was last on GZERO World just weeks before the pandemic hit in the fall of 2019 and he described at the time what kept him up at night: a "pandemic-like respiratory illness." This time, he'll talk about how closely that nightmare scenario foreshadowed the COVID-19 pandemic. He'll also offer some guidance about what public health measures vaccinated Americans should continue to take in the coming months (hint: masks stay on).