Saturday, July 25, 2020

Why do asymptomatic COVID-19 cases even happen?

Health officials are concerned about why some people who test positive for the coronavirus never feel sick. Could it be the luck of genetics? The blessings of youth? Or something else?

Medical students attend to people experiencing homelessness in a park in Prague during the COVID-19 pandemic. Photograph by Milan Bures, Anzenberger via Redux

By Sarah Elizabeth Richards, National Geographic

The facts of COVID-19 include this disturbing reality: We have little idea who among us is spreading the disease.

Up to half of stealthy spreaders “feel fine” on Saturday night—but by the time they come down with the telltale cough, fever, and fatigue on Monday, they’ve potentially infected multitudes. Meanwhile, what could be an even more elusive bunch—people who are infected with the coronavirus but never, ever feel sick—make up 40 percent of infections in the United States, according to estimates from the Centers for Disease Control and Prevention.

What’s especially puzzling is why these two groups—presymptomatic transmitters and asymptomatic cases—appear so frequently. Other viruses, such as influenza and colds, spread silently too. But the extreme evasiveness of COVID-19 makes it harder to control.  Read more >>