Speed Reads

the coronavirus crisis

Is the CDC exaggerating the risk of outdoor COVID-19 transmission?

The Centers for Disease Control and Prevention's official stance is that "less than 10 percent" of COVID-19 transmission has occurred outdoors, but The New York Times' David Leonhardt wrote Tuesday that that's like saying "sharks attack fewer than 20,000 swimmers a year." Sharks actually only attack around 150 people a year, so the 20,000 number is "both true and deceiving," which appears to be the case with the CDC's outdoor transmission assessment.

In reality, multiple epidemiologists told Leonhardt the actual figure is probably less than 1 percent, and may even be below 0.1 percent. The 10 percent benchmark "seems to be a huge exaggeration," said Dr. Muge Cevik, a virologist at the University of St. Andrew's.

The CDC reportedly reached that number based on research that defined any place that was a mix of indoors and outdoors as the latter. For instance, the bulk of cases tied to outdoor transmission in multiple studies occurred at construction sites in Singapore, which the Times reports were not solely outdoor settings, leaving open the possibility that transmission really occurred indoors. But even if all of the Singapore cases did occur outside, they still only made up less than 1 percent of total cases.

Increasing the risk by tenfold or more is an issue, Leonardt argues, not because it's bad math, but because it's "an example of how the agency is struggling to communicate effectively, and leaving many people confused about what's truly risky." Read more at The New York Times.