The coronavirus has killed more than 1,300 people, brought a huge swath of central China to a standstill and rattled millions around the globe with hints of a pandemic seen in Hollywood fantasies.

But the virus’s destructive potential has overshadowed one encouraging aspect of this outbreak: So far, about 82 percent of the cases — including all 14 in the United States — have been mild, with symptoms that require little or no medical intervention. And that proportion may be an undercount.

Health authorities managing the outbreak are trying to understand what that critical fact portends. Are the 60,000 sick people tallied so far just a portion of a vast reservoir of uncounted victims, some of whom may be spreading the disease? And do the mild illnesses reveal characteristics of the virus itself — something that could be useful in crafting a more effective response?

“The fact that there are so many mild cases is a real hallmark of this disease and makes it so different from SARS,” said Jennifer Nuzzo, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health’s Center for Health Security. “It’s also really challenging. Most of our surveillance is oriented around finding people who require medical intervention.”