“The Destroying Monster Continues the Work of Destruction Making a Vast Graveyard of Stricken Cities.” That is how a newspaper headline from Little Rock, Ark., described a yellow fever outbreak in 1878. The mosquito-borne illness infected 120,000 individuals and killed between 13,000 and 20,000 during the spring and summer of that year in the southern U.S.

What is most relevant to the current coronavirus pandemic is not how the yellow fever killed people. It is how the disease changed society for those who remained.

“I’ve seen examples of young men hopping into the beds of their recently dead friends,” says Kathryn Olivarius, an assistant professor of history at Stanford University, regarding historical accounts of people seeking to become immune to the illness in the 1878 outbreak. “They were literally risking their lives—seeking sickness as a pathway to prosperity.”

Yellow fever in the U.S. at that time—and earlier, smallpox in Europe in the 1700s—brought with it an understandable fixation on immunity. In the current coronavirus pandemic this attitude has been globally reborn in the form of an “immunity passport.” The idea is that if individuals successfully weather COVID-19, they could be allowed to reenter work and public spaces. There are fundamental problems with this concept, however, because of the many unknowns surrounding coronavirus immunity itself.