WEDNESDAY, Aug. 12, 2020 — Respiratory droplets called aerosols floating in the air do carry coronavirus that can infect people, The New York Times reported Tuesday.
This finding may appease those who are skeptical this could occur.
“This is what people have been clamoring for,” Linsey Marr, an expert in airborne spread of viruses who was not involved in the work, told the Times. “It’s unambiguous evidence that there is infectious virus in aerosols.”
Researchers from the University of Florida have found live virus in aerosols collected at distances of seven to 16 feet from hospitalized COVID-19 patients. That’s more than the 6 feet recommended for social distancing.
The results of the study were available online last week, although they haven’t been peer-reviewed.
Yet they have already caused a stir. “If this isn’t a smoking gun, then I don’t know what is,” Marr tweeted.
Some experts, however, say it’s not clear that the amount of virus found was enough to cause an infection, according to the Times.
“It’s very hard to sample biological material from the air and have it be viable,” Shelly Miller, an environmental engineer at the University of Colorado Boulder who studies air quality and airborne diseases, told the Times.
“We have to be clever about sampling biological material so that it is more similar to how you might inhale it.”
In this new study, researchers made a sampler that uses water vapor to enlarge the aerosols so they can be collected from the air.
The device transfers the samples to a liquid containing salts, sugar and protein, which preserves the virus.
“I’m impressed,” Robyn Schofield, an atmospheric chemist at Melbourne University in Australia, who measures aerosols over the ocean, told the Times. “It’s a very clever measurement technique.”
The researchers took air samples from a room dedicated to COVID-19 patients at the University of Florida Health’s Shands Hospital.
Neither patient in the room had any procedures that generate aerosols, which the World Health Organization has said is the main source of airborne virus in hospitals.
Genetic analysis of the virus in the aerosols, however, showed that the virus was the same as that of an asymptomatic patient newly brought into the room.
Room air was changed six times per hour and was fitted with filters, ultraviolet light and other measures to kill the virus before the air was introduced into the room.
These precautions might explain why only 74 virus particles per liter of air were found, researcher John Lednicky, a virologist at the University of Florida, told the Times.
Rooms without good ventilation, such as schools, might have a lot more virus floating in the air, he said.
But some experts disagree.
“I’m just not sure that these numbers are high enough to cause an infection in somebody,” Angela Rasmussen, a virologist at Columbia University in New York, told the Times.
“The only conclusion I can take from this paper is you can culture viable virus out of the air,” she said. “But that’s not a small thing.”
The distance at which the team found virus is much more than the recommended distance for physical distancing, some experts said.
“We know that indoors, those distance rules don’t matter anymore,” Schofield said. The 6-foot minimum is “misleading, because people think they are protected indoors and they’re really not,” she said.
These findings should make people take precautions like improved ventilation, Seema Lakdawala, a respiratory virus expert at the University of Pittsburgh, told the Times.
“We all know that this virus can transmit by all these modes, but we’re only focusing on a small subset,” Lakdawala said.
One odd finding is that the researchers found just as much viral RNA as they did infectious virus when other methods found about 100 times more genetic matter.
“When you do nasal swabs or clinical samples, there is a lot more RNA than infectious virus,” Lakdawala said.
Lednicky said he would check his numbers again to be sure. But in any event, the message is clear, he said.
“We can grow the virus from air — I think that should be the important take-home lesson,” he told the Times.
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