Scientists Say Airborne Coronavirus Fuels Superspreader Events
White House outbreak illustrates the risk of an underappreciated Covid-19 infection route, scientists say
The coronavirus spreads significant distances indoors via invisible aerosols that can linger for hours, building up and causing superspreader events that can infect several people, a group of virus-transmission experts emphasized in an open letter published today in the online version of the journal Science. This airborne transmission is likely the most prevalent path for Covid-19 infections, they say, adding that health officials must communicate this risk more clearly.
“The reality is that airborne transmission is the main way that transmission happens at close range with prolonged contact,” says one of the letter’s co-authors, Donald Milton, MD, an environmental health professor at the University of Maryland and an expert on airborne infections. “You can’t take your mask off at six feet.”
The indoor superspreader risk has been known for months and communicated frequently by scientists since the spring. But outdated research based on science from the 1930s had caused many public health officials and agencies to focus on the six-foot circle of supposed protection.
Even that guideline, considered by scientists to be a helpful minimum at best, has been routinely flouted by President Donald Trump and White House officials, apparently leading to the ongoing outbreak of Covid-19 among people who attended the Supreme Court nomination ceremony September 26.
“One is far more likely to inhale aerosols than be sprayed by a droplet, and so the balance of attention must be shifted to protecting against airborne transmission.”
The six-foot guideline is important, scientists say, but it’s just one layer of protection, a minimum measure that reduces some of the risk of infection, including from larger respiratory droplets that fall to the ground quickly. Aerosols are smaller droplets emitted just by breathing, and more so when talking, and in yet greater quantities if shouting or singing, as well as in a cough or sneeze.