The Centers for Disease Control and Prevention released new guidance on Friday about how far apart children ought to be while in school. The old standard of 6 feet has been replaced by a 3-foot minimum, which will make it much more feasible for many schools to reopen for full-time instruction in person.
The adjustment applies only to schools, not society more broadly, and only when prevalence is low and schools are taking other measures, such as keeping kids in social “pods.” The preconditions may preclude the guidance from having its full intended effect. The World Health Organization has allowed 1 meter of distance (around 39 inches) both in and out of school. China, France, Denmark and Hong Kong, among others, went with this spacing. If the CDC’s guidance were applied universally—to include work and retail—that one adjustment could restore substantially more commercial activity.
More distance is always better when it comes to contagion. But the 6-foot directive might have been the single costliest measure CDC has recommended, which have been largely followed over the past year. So what science went into making—and, more important, sustaining—the recommendation?
Nobody knows for sure. Most agree the guideline derives from a belief that Covid is largely spread through respiratory droplets, like flu. Old studies suggest that larger respiratory droplets are unlikely to travel more than 6 feet, and therefore close contact with an infected person is the primary mode of exposure. This research was hardly conclusive, but by most accounts it formed the basis for the initial Covid recommendations. More-recent research shows that the novel coronavirus can also spread through airborne particles, known as aerosols, especially indoors.
Most planning for a pandemic prepared for a bad flu outbreak. Given how little was known about Covid, it was reasonable to base early assumptions on the flu blueprint. But this doctrine wasn’t revisited as more data became available about the novel coronavirus. The reliance on a flu model caused public-health authorities to underestimate and overestimate Covid in important ways.
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