Five COVID numbers that don't make sense anymore

6 feet + > 15 minutes = close contact

Since the pandemic’s early days, Americans have been taught to benchmark our risk of exposure to the virus by two metrics: proximity and duration. Get within six feet of an infected person for at least 15 minutes over a 24-hour period, and congratulations—you’ve had a “close contact.” Even now, the CDC advises that this kind of encounter should trigger 10 full days of masking and, depending on your vaccination status and recent infection history, a test and/or a five-day quarantine.

Thresholds such as these made some sense when researchers weren’t yet savvy to the virus’s main modes of transmission, and at least some efforts were made to contact trace, Jetelina told me. “You needed some metric so you could call people.” Nearly all contact-tracing attempts, though, have long since fizzled out. And scientists have known for years that SARS-CoV-2 can hitch a ride in bubbles of spittle and snot small enough to drift across rooms and remain aloft for hours, especially in poorly ventilated indoor spaces. Pathogens don’t slam up against a magic wall “at the six-foot mark,” Malaty Rivera said. Nor will viruses bide their time for 14 minutes and 59 seconds before launching themselves noseward at 15 minutes on the dot. Exposure is a spectrum of high to low risk” that factors in, yes, proximity and duration, but also venue, ventilation, mask quality, and more, Popescu said. “It’s not just ‘exposed’ or ‘not exposed.’”

The CDC acknowledges that SARS-CoV-2 can move beyond six feet—but the scientific justification behind its guidelines on preventing transmission was last updated in May 2021, just before the Delta variant bamboozled the nation. Since then, the coronavirus has gotten even more contagious and crafty—better at transmitting, better at dodging the antibodies that people raise. “Even passing interactions and encounters have led to people becoming exposed and infected,” Malaty Rivera said, especially if people are indoors and a ton of virus is being volleyed about. And yet, the mantra of “six feet, 15 minutes” has stayed. Schools have even cut the guidance in half, counting close contact only when children are less than three feet apart.