NEW YORK (GZERO MEDIA) - The Spanish flu virus of 1918 killed an estimated 50 million people, more than all the deaths in World War I combined.

While global public health efforts have greatly improved mortality rates in more modern outbreaks, experts say the next pandemic is a matter of "when", not "if".

In this episode, American foreign policy expert Ian Bremmer takes a look how diseases spread and become global. His guest, Dr Anthony Fauci, is a leading epidemiologist and director of the National Institute of Allergy and Infectious Diseases at the US National Institutes of Health.

This video is made available to The Straits Times under a partnership with GZERO Media, a subsidiary of the Eurasia Group.