The controversy over aerosol transmission of the coronavirus may have been resolved, thanks to research from the University of Florida (medRxiv, Aug. 4, 2020). Investigators there report that they were able to isolate viable SARS-CoV-2 in aerosols at a distance of 7 to 16 feet from infected patients. That’s right, coronavirus particles that could transmit COVID-19 were captured in the air well beyond the magical 6 feet.
The Aerosol Transmission of Coronavirus Particles:
This is the first time researchers have been able to demonstrate that coronavirus particles found in the air can survive and infect cells. This viral transmission occurred in a hospital room where there was good ventilation, highly effective filtration and UV air purification.
It challenges the traditional view that only large droplets transmit the virus. The World Health Organization has held that maintaining a distance of 6 feet is adequate. The new research calls that assumption into question!
Why Is This the “Smoking Gun” Of Aerosol Transmission?
Professor Linsey Marr is the expert on viral spread through air. Please trust us when we say that Dr. Marr is the go-to researcher when it comes to how airborne pathogens are transported through air.
You dare to doubt us? Dr. Marr graduated Summa Cum Laude from Harvard. Her undergraduate degree was in engineering. She received her doctoral degree from the University of California, Berkeley in environmental engineering. Dr. Marr’s postdoctoral research was at MIT. She holds an endowed chair at Virginia Tech. Dr. Linsey Marr has been the person everyone turns to when it comes to understanding how coronavirus particles move through the air around us.
Here are some quotes from Dr Marr regarding the University of Florida research:
In the New York Times (Aug. 11, 2020) she was quoted:
“This is what people have been clamoring for. It’s unambiguous evidence that there is infectious virus in aerosols.”
Here is her Tweet from Aug. 6 about the University of Florida research:
“If this isn’t a smoking gun, then I don’t know what is. Successful isolation (cytopathic effect) of SARS-CoV-2 in aerosols collected 2-5 m from patients, genome identical to NP swab, TCID50:genome copies close to 1:1! /1”
Are you a bit confused about the scientific jargon? Please watch this video aired on the CBS Evening News. Dr. Jonathan LaPook anchored this segment with the University of Florida researcher, Dr. John Lednicky. You will also see Dr. Linsey Marr.
Dr. Marr Tweeted this about the latest research on coronavirus particles in air:
“*If* the concentrations in air reported here are correct, then you would breathe in 1000 virions (infectious virus particles) in about 5 minutes in this room. Not all will stick. Need to know carrier aerosol size to predict how many deposit and where in the respiratory tract.”
Droplets vs. Aerosols?
We know that people are still very confused about droplets vs. aerosols. The WHO has been insisting that coronavirus particles float on big droplets that fall to the ground within six feet. Dr. Marr offers this easy-to-understand explanation of the difference in size:
“…droplets are like spraying Windex, aerosols are like from a fog/smoke machine.”
Still confused? Here is Dr. Marr’s explanation as heard during an interview with Stan Bunger on KCBS radio on July 21, 2020:
Q. And to be clear, can you define the difference between droplets and aerosols?
“Yeah, droplets and aerosols – there’s a smooth transition between them. So droplets are bigger, aerosols are smaller. An aerosol is really just a small version of a droplet, it’s so small that we can’t see it. But you know that when people cough or sneeze or sometimes when they talk – I know when I talk, sometimes these large droplets fly out and get on my computer screen. But for every one of those that we see, there are hundreds to thousands more of the microscopic ones, and we call those aerosols because they can stay floating in the air for minutes to hours and we can breathe them in. In contrast, the large droplets, if I’m in a Zoom meeting sitting at my computer, those fly straight from my mouth and hit the screen or if there’s someone there they could hit the person, if it lands in their eyes or their nose or their mouth, it can cause infection. But at the same time there’s this cloud of aerosols that we can’t see that’s coming out, too.”
The Take Home Message on Coronavirus Particles in Air:
No one knows how the University of Florida research will affect policy makers. Most indoor spaces do not have the kind of ventilation, high-efficiency air filtration or ultraviolet air purification found in hospitals. The fact that the coronavirus can remain viable even in such locations makes offices, restaurants, bars, churches, banks, supermarkets and even schools seem far riskier than many people imagine.
The lead investigator at the University of Florida who did the research on coronavirus particles notes in an interview with the New York Times that:
“We can grow the virus from air — I think that should be the important take-home lesson.”
The Implications of this Research:
What does that mean for you and those you love? Viable coronavirus particles can float in the air. They can be harvested at distances at least 16 feet from their source and infect cells.
The authors of the University of Florida study offer this conclusion to their work:
“Our findings reveal that viable SARS-CoV-2 can be present in aerosols generated by a COVID-19 patient in a hospital room in the absence of an aerosol-generating procedure, and can thus serve as a source for transmission of the virus in this setting. Moreover, the public health implications are broad, especially as current best practices for limiting the spread of COVID-19 center on social distancing, wearing of face-coverings while in proximity to others and hand-washing. For aerosol-based transmission, measures such as physical distancing by 6 feet would not be helpful in an indoor setting, provide a false-sense of security and lead to exposures and outbreaks.”
We know that SARS-CoV-2 is highly infectious. At last count, over 20 million people worldwide have caught COVID-19. In the U.S. the number of cases is over 5 million. As we write this, 167,000 people in the U.S. have died from COVID-19. There are many examples of people catching COVID-19 while singing, attending church services, weddings or funerals. We have written about ventilation concerns at this link.
Still Arguing Over Aerosol Transmission of COVID-19!
How do people catch the coronavirus? How effective are face masks for preventing the transmission of COVID-19? Scientists lack clear answers!
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