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.”