A Health Mystery at the Epicenter of COVID-19

Editor’s note: Paul Salopek is walking across the world for a storytelling project called the “Out of Eden Walk.” His periodic essays on science, culture, writing and other topics of interest to students and media professionals will be posted by Pulitzer Center on Crisis Reporting as part of an ongoing series on slow journalism.

YANGON, Myanmar.

Last spring, during the first dark bloom of the global Covid-19 pandemic, the Myanmar government was roundly mocked for declaring its citizens miraculously immune to the ravages of the deadly virus.

“Covid-19 is still not present in Myanmar,” U Zaw Htay, an information ministry spokesman, blandly assured reporters in March, when his country was reporting no cases. “The lifestyle and diet of Myanmar citizens are beneficial against the coronavirus.”

U Zaw Htay was ridiculed at the time as a propagandist. (A label that resurfaced when he recently joined the ranks of a military coup.) But at least in terms of public health—what a difference a plague year makes.

Covid-19, of course, has spread through Myanmar. But even in the midst of the current global surge, the impoverished Southeast Asian nation is logging fewer than 600 infections a day among a population of 54 million. Other nations in the region such as Laos, Malaysia, Vietnam, Singapore, Taiwan, Malaysia and China, also are recording similar, mysteriously low caseloads of the novel coronavirus, or SARS-CoV-2, with daily totals veering between zero and low thousands. Such numbers are vastly eclipsed by the tens of thousands of cases being registered a day in many European nations. And they fade to near-invisibility against a peak of 120,000 new cases a day that sickened the United States in recent weeks. Indeed, US deaths from Covid-19 during any 24-hour period this past week—3,230 Americans perished on Thursday, for example—exceed all the lives swept away in Myanmar, a mid-sized country, since the pandemic began.

Scientists are still puzzling over East Asia’s and Southeast Asia’s relative immunity from a brutal disease that so far has killed more than two million people across the world. But all agree on one thing: The regional imbalance is real. It’s not a fluke of patchy testing.

So what’s going on?

Like the Myanmar bureaucrat, some experts cite cultural factors: Many people in Asia don’t practice transmission behaviors like handshaking, and millions live in well-ventilated village homes. Others point to weather: The virus’ ferocity appears to wilt somewhat in tropical climates. Draconian government quarantines and tracing policies, whether enforced by technocratic or authoritarian regimes, also play an obvious role in easing Asia’s sickness and death, health experts say. But perhaps the most intriguing factor may involve deep history: an ancient local dance with viruses.

“I think its pretty clear that there is some preexisting human immunity to coronaviruses in parts of Southeast Asia,” says Spencer Wells, a geneticist who led The Genographic Project for the National Geographic Society. “I’m sure people have been exposed to these sort of things all the time there. Not this virus. But others that are close enough.”

Virus hunters have yet to pinpoint the exact natural source of Covid-19.

Early evidence points to an obscure microbe harbored by horseshoe bats in Yunnan, China. That species of coronavirus shares 96% of its DNA with SARS-CoV-2. Another candidate, a bat virus recently isolated in Cambodia, shows a 92% genetic match. Bat-to-human microbial infections are nothing new in the region. Severe Acute Respiratory Syndrome, or SARS, sprang from bats southern China. And given that the broader region, including Southeast Asia, is host to a winged cornucopia of more than 100 bat species, more bat-borne coronavirus outbreaks seem inevitable—especially as Homo sapiens populations chew relentlessly into remaining natural habitat.

What remains a mystery, however, is whether background exposure to such native coronaviruses—in the soil, in the air, in food—to some degree helps inoculate local human populations. Put another way: During a Covid-19 plague, is it good to be Southeast Asian?

“Our antibodies aren’t afraid of any viruses,” joked Ko Win Aung, the leader of a Covid-19 response committee in Mandalay, Myanmar’s old imperial capital of 1.5 million on the banks of the Irrawaddy River. “Our national health system is so limited that we’re forced to survive illness by ourselves. That’s why they say our DNA is resistant to Covid.”

Yet proof of genetic shielding, of an inherited immunity against Covid-19 in Asia, is scarce.

Japanese scientists are studying Asian and European populations for subtle differences in the genes regulating immune responses to viruses— human leukocyte antigen (HLA) haplotypes —seeking some evolutionary role. Conclusive results aren’t in.

More promising are ghostly medical clues hinting at past coronavirus epidemics: nature’s own herd-immunity vaccinations.

Again in Japan, a researcher named Tatsuhiko Odama discovered that every patient in his epidemiological studies scrambled an unusually fast antibody defense to Covid-19. This suggests a Covid-like virus may have burned through the population earlier, priming immune systems for the new invader. (A similar protective effect was found among some children in the UK previously exposed to common cold viruses.)

These findings square with my own boot-level observations of viral resistance seen while trekking across Southeast Asia.

Villagers living in intimate contact with the environment usually aren’t the sickest populations I encounter, at least in terms of infectious disease. (Though they’re unquestionably the poorest.) It’s wealthier urbanites inhabiting antiseptic bubbles, far from nature, who’ve got the chronic sniffles.

“People who live in cities for multiple generations don’t have the same wild virus exposure in childhood,” says geneticist Wells. “They’re going to get hit hard when pandemics happen. It pays to be down in the dirt.”

A parting lesson of Asia’s enigmatic Covid-19 resistance: Just as wild viruses need us, we apparently need them.