“For the most part, we live in an uncomfortable equilibrium with bacteria and viruses, both those inside of us and those outside, in the natural world. But every now and then, the war reignites. An old pathogen, long dormant, returns. A new mutation emerges. Those events are the epidemics and pandemics we confront. They are the battles we fight.

“Success for humanity means winning every battle. The stakes are high. Around the world, disease is the one enemy that unites every person of every race and nationality. When a pandemic occurs, we come together in a single, species-wide cause.

“In the history of our battle against pandemics, there have been lulls and wildfires, peaks and valleys. It is the wildfires we know well; they are committed to history. They are the times when we lost the battle. They are the dark years when the human race died en masse. When our population shrank. When we cowered and waited.”

The screen changed to a painting of Europeans with bumps covering their bodies.

“In the third century, the Antonine Plague wiped out a third of Europe’s population. And just when population levels were recovering, the Plague of Justinian in the sixth century killed almost half of all Europeans; up to fifty million people died from what we believe was bubonic plague.

“In the 1340s, the Plague once again remade Europe, forever changing the course of world history. At that time, we believe the world population was around 450 million. The Black Death killed at least 75 million. Some estimates go as high as 200 million. Imagine, in the span of four years between twenty and fifty percent of the world population dying.

“Europe, because of its large cities, population density, and advanced trade routes, has repeatedly been a hotbed for pandemics. But it is not alone.”

The image switched to a picture of Spanish conquistadors meeting indigenous tribes at a shoreline, their wooden ships anchored in a bay behind them.

“Consider the New World when Europeans arrived. We’ve heard so much about the plight of native peoples in the present-day United States, but consider the populations of New Spain, present-day Mexico. In 1520, smallpox killed nearly eight million. Twenty-five years later, a mysterious viral hemorrhagic fever killed fifteen million—roughly eighty percent of their population at the time. Imagine that: a mysterious illness killing eight out of every ten people. In America, that would be over 240 million people. It’s unthinkable, but it happened, right here in North America, less than five hundred years ago. We still haven’t identified the pathogen that decimated Mexico in the sixteenth century, but we do know it returned twenty years later, in 1576, following two years of drought. It killed another two million from the already decimated population. To this day, we still have very few clues about what caused that pandemic. Most importantly, we don’t know if or when it will return.”

The image changed to a black-and-white photo of a field hospital with rows of iron single beds holding patients covered by wool blankets.