When a Chinese exchange student developed symptoms suggestive of the coronavirus that emerged in December in his native country, Philadelphia’s William Penn Charter School did the right thing. It worked with health officials to test and quarantine the teenager.

But reaction to the suspected case turned the esteemed Quaker school — dedicated to principles of “mutual respect, equality, community” — into a microcosm of the growing global panic over the new upper respiratory illness.

Penn Charter students stayed home in droves. Local schools canceled athletic events with Penn Charter teams. A school bus driver tried to deny rides to Penn Charter, while a medical professional canceled an appointment with a student. The 18 Chinese exchange students, meanwhile, felt like outcasts.

“This is not the experience we wanted for them,” Penn Charter head Darryl J. Ford wrote in a Jan. 27 email informing parents that the tested student did not have the coronavirus — but the exchange program was being axed anyway.

For social scientists, the latest overreaction is déjà vu. The 2002 outbreak of SARS (severe acute respiratory syndrome) in China tapped into anxieties about globalization, immigration, economic disruption, national security, bioterrorism, and more. Now, digital and social media make the fear and loathing even worse.

“The saturation of a 24/7 news media creates the effect of an impending apocalypse,” said Duke University English professor Priscilla Wald, author of the book Contagious: Cultures, Carriers, and the Outbreak Narrative. “The threat of a pandemic should not inspire paralysis. It should be a reminder that access to health care should be a basic human right and a priority.”

The World Health Organization on Sunday decried the “massive infodemic” that has bombarded people with information, “some accurate and some not.”

The psychology of pandemics — epidemics that circle the planet — has always been a product and shaper of cultural angst.

Consider that the global scourge known as the seasonal flu kills between 12,000 and 60,000 people every year in the United States, according to federal data. In a bad year, 40 million Americans are infected. Yet most Americans don’t bother to get a flu shot.

Meanwhile, the official coronavirus toll globally hovered near 15,000 cases on Sunday — only 146 outside China. There have been 304 deaths, all in China save for one in the Philippines. The U.S. has 11 confirmed cases, none in the Philadelphia area, where stores are nonetheless running out of face masks. (Experts say ordinary surgical masks are not very helpful.)

“The flu is something we’ve had around; more is known about the flu,” said Carole Kenner, dean of the College of New Jersey’s School of Nursing, explaining the seemingly illogical behavior. “It’s partly the fear of the unknown.”

To be sure, the unknowns are unnerving. A cluster of coronavirus cases in Germany suggests the infection can occasionally be spread during the incubation period — up to two weeks — even before symptoms appear. China’s drastic quarantine and travel restrictions may not snuff out the disease. And developing a vaccine could take more than a year.

Then again, the new virus seems to be much like the flu: moderately contagious, often so mild that people don’t get a formal diagnosis, and hardest on the elderly and infirm. The mortality rate is well below 1%, based on a study in the Lancet that estimated the true number of coronavirus infections, including mild ones, at about 75,000 late last month.

Before modern medicine and infection control, pandemics were truly devastating. Bubonic plague, which decimated medieval populations in Europe and Asia, upended international trade, the labor supply, feudal control of peasants, faith in God, and the church’s power. A century ago, an especially virulent strain of influenza killed millions across the globe, including 20,000 just in Philadelphia.

These days, it’s the fear of pandemics that’s truly devastating. Many governments, companies, and airlines have restricted travel and trade with China — even though the WHO says that it’s unnecessary. Chinese stocks plunged 8% on Monday, the worst day in years, as the country’s markets reopened after an extended holiday break.

In Italy, a cruise ship quarantined thousands of tourists for a day last week until a Chinese passenger with a fever tested negative for the virus.

“This virus thing is becoming a psychosis,” an Italian citizen told the New York Times while she waited to board the ship.

Fear often goes hand in hand with persecution and prejudice. The Nazis isolated Jews in ghettos on the pretense that they carried diseases. When syphilis first broke out in Europe in the 1400s, the English and Italians called it the French disease; the French called it the disease of Naples; Poles called it the German disease; Russians called it the Polish disease; and so on.

Now, Chinese nationals are feeling the stink eye. Sam Phan, a master’s student at the University of Manchester, wrote in the British newspaper the Guardian: “This week, my ethnicity has made me feel like I was part of a threatening and diseased mass. To see me as someone who carries the virus just because of my race is, well, just racist.”

Harvey Rubin, a University of Pennsylvania infectious disease specialist who has helped to review Philadelphia’s pandemic preparedness, was unsurprised by the panic. “People use any excuse,” he said, “to confirm their own robustly held biases and bigotry.”