But perhaps none have such a horrific ending as the cocoliztli epidemic in 16th-century Mexico, estimated to have killed up to 80% of the country’s native population in a mere three years. 

A hemorrhagic fever featuring jaundice, dementia, and blood spilling from bodily orifices, it was brought by Spanish conquistadors, who seemed virtually immune to it, according to a 2004 article in an Oxford medical journal. But it burned like wildfire through the native population, which represented what researchers refer to as “virgin soil” due to their lack of prior exposure.

When the Spaniards arrived in 1519, Mexico’s population was estimated to be anywhere from 15 million to 30 million. Less than a century later, it had been gutted to a mere 2 million.

There’s a reason books and movies about the cocoliztli pandemic don’t exist, says Arijit Chakravarty, a COVID researcher and CEO of Fractal Therapeutics, a drug development firm.

“A science-based case can be made that not all pandemic stories are happy-ending stories,” he tells Fortune, referencing the cocoliztli epidemic, among other nearly forgotten but relentlessly brutal depopulating epidemics.

“There’s a reason that pandemics are underrepresented in our literary traditions—they don’t fit the criteria of a ‘good story,’” with distinct closure that ties up loose threads, Chakravarty says.

Perhaps this is why the COVID-19 pandemic keeps “ending,” he posits. Headlines from each year of the pandemic so far claim the sun is setting on the global health emergency, just as it supposedly is now.

But “in the real world, viruses don’t have to sign a screenwriter’s contract,” he says. “The hero’s-journey template doesn’t apply in the real world—there’s no contractual guarantee of a redemptive arc.”

‘Binged out’ on COVID

Plagues and pandemics have become a popular trope in movies like Outbreak, Contagion, The Flu, and The Cassandra Crossing. They’re frequently used as a plot device in the Bible. The Shirburn Ballads, written in the Middle Ages, depict a pandemic as a fire-breathing dragon, scorching maidens with his hot, unrelenting breath.

“Movies like Contagion and Outbreak have beaten the concept of grisly viral death to death,” Chakravarty says. “In both, the virus is an enemy that is easily defeated within the time constraints of a feature-length movie. Two hours and 20 minutes in, and biomedical science has whupped its ass.”

He continues: “That’s the funny thing—accounts of disease outbreaks and pandemics always end with the disease getting it in the shorts, right? Because what kind of movie would it be if the closing credits rolled on scenes of mass mortality and morbidity?”

Cinematic portrayals of pandemics are unrealistic, but it doesn’t stop the public from basing expectations on them, says Traci Hong, a professor of media science at Boston University.

“We generally process information that is packaged in stories more easily and more readily,” she says. “There’s a beginning, drama, and then some resolution that leads to an end. Beginning and end are the bookmarks of the conflict.”

“People are looking for the other bookmark, basically.”

A lack of a definitive end to the COVID-19 pandemic leaves many searching for one—and “if there’s not a definitive end from a government or health agencies, people create their own endings. It’s a natural way for people to make sense of the world,” Hong says. 

Americans “are seeing this pandemic unfold in the media—it’s almost like a series they would watch on streaming.” There’s a reason society keeps fabricating its own conclusions, she says: A typical series runs three to five seasons, usually 26 weekly episodes each. 

“Twenty-six weeks per season, running five seasons—that’s roughly 130 weeks of showtime,” Hong says. “That’s roughly two and a half years of watching the same show, if you watch it every week. They’re binged out. It’s well run the course of a typical series lifespan.”

“It reminds me very much of [the movie] The NeverEnding Story.“

A new ‘chronic human condition’

By author Brian Michael Jenkins’s estimation, the rose-colored glasses so many Americans are wearing filter reality through a number of lenses of bias.

“We like to think of pandemics as finite events, that when the pandemic is over, we can return to some kind of pre-pandemic normality,” says Jenkins, author of Plagues and Their Aftermath: How Societies Recover from Pandemics, releasing this fall, and senior advisor to the president of RAND Corporation. The former Green Beret also served on the White House Commission on Aviation Safety and Security after being appointed by then President Bill Clinton and served as an advisor to the National Commission on Terrorism.

“Looking at this historically, that’s not the case.”

“False hopes” and “cognitive biases” cause hopeful individuals to “often turn their hopes into assumptions,” Jenkins says. “If you’re hoping for a positive outcome, that can affect our assessments, and we tend to slide from hope into an assumption.”

Another psychological lens in the rose-colored glasses: “anchoring bias.”

“The first information you receive affects all the subsequent information you receive, especially if that first information comes from a source that one respects,” he says. “Especially in the U.S., but not exclusively, the official line at the beginning of the pandemic was, ‘This will be over in a couple of months.’”

But predictions of a cure-all vaccine and herd immunity didn’t pan out.

“That anchoring bias sets in people’s minds a notion that, all right, this is something that is going to be over quickly. Once that is set in our mind, once it becomes the anchor, subsequent events are either dismissed or reinterpreted,” Jenkins says.  

There’s also the “normalcy bias,” Jenkins says, that convinces people not to take extreme action in the face of a threat because “it’s such a departure from normalcy that your mind simply rejects the terrible outcome that could occur.”

COVID has been an easier pandemic to reject than some that occurred in antiquity, Jenkins says—there aren’t bodies in the streets.

“When you have something that is killing 25%, 50% of a population, you don’t need a lot of convincing to tell you that this is extremely dangerous,” he says.

U.S. COVID deaths comprise far less than 1% of the country’s population, and “while that’s a tragic number that turns out to be [around] a million people, with such a low percentage, people can say, ‘It’s not too bad. We can deal with that.’”

Such acceptance is fortunate for U.S. public health officials, who have altered course and are now sending a message of coexisting with the virus.

But society will have to divorce its expectations of a quick, clean ending to the COVID-19 pandemic and come to terms with something unsatisfying and “very ragged,” Jenkins says.

“The notion of eradicating the virus is simply not realistic. Instead of the virus coming to an end, waves of new variants wash back and forth across the planet. And that will complicate recovery. In a sense, we’re talking about something that becomes a chronic human condition.”