Every day, new evidence emerges of the havoc that COVID-19, the disease caused by the coronavirus, is wreaking all around a thoroughly globalized world. As a new pathogen sweeps nations and continents, people are being quarantined in hospitals and aboard ships in distant ports, and the movement of labor and vital supplies has been profoundly disrupted. What’s becoming clear—from China to Iran to Italy to the United States—is that the new pathogen isn’t the only thing putting human life at risk. The shortages and other disruptions that an epidemic causes, not to mention the social inequities that it aggravates, massively amplify the consequences caused by the disease itself.

And yet these dynamics—far from being unique to the current epidemic—have recurred time and again for at least half a millennium. As a historian of slavery and medicine, I often come across bleak accounts of smallpox outbreaks that happened 200 to 500 years ago. Then as now, the poorest and least powerful people were usually at the greatest risk of infection—and the public-health measures of the time either neglected these people or actively harmed them. This treatment frequently enabled otherwise containable disease outbreaks to spread.

In my historical research, I study the period from 1500 to 1800, a three-century span during which millions of people endured warfare, displacement, confinement, labor exploitation, insufficient access to medical treatment, and unsanitary living conditions. This period was also defined by then-unprecedented levels of regional and global travel, trade, conflict, and forced and voluntary migrations.

During the period I study, everyone’s well-being was at some risk in some way during a smallpox epidemic, regardless of whether a person was the colonist or the colonized, the enslaver or the enslaved, rich or poor, or of African, Native American, or European descent. The first recorded smallpox outbreak in the Americas struck the Caribbean roughly 500 years ago; a European man arrived on the Caribbean island of Hispaniola carrying the disease in 1518. This outbreak ultimately killed thousands of free and bound Taíno people who performed agricultural and mining labor on the island. Many Native Americans were particularly vulnerable during smallpox outbreaks because they had not previously been exposed to the disease and were therefore not immune.