Aerosolization of SARS-CoV-2

I want to review stories such as this one from CNN: Experts tell White House coronavirus can spread through talking or even just breathing.

The headline itself is sensational and while the article does mention some of the caveats about that possibility it does not caveat the statement “Research by the University of Nebraska shows that genetic material from the virus was found in patients’ rooms more than 6 feet away from the patients, according to the letter.”

The letter itself can be found here Rapid Expert Consultation Update on SARS-CoV-2 Surface Stability and Incubation for the COVID-19 Pandemic (March 27, 2020) With a follow up at Rapid Expert Consultation on the Possibility of Bioaerosol Spread of SARS-CoV-2 for the COVID-19 Pandemic (April 1, 2020)

Each of these have some notable quotes relevant to how concerned someone might be about Aersolized SARS-CoV-2 and some of questions of transmission are based on studies of previous viruses.

I’ll start with Page 3 under B. Natural history Studies Starting 3 lines down “All samples were tested using reverse transcriptase-polymerase chain reaction (RT-PCR). There were no efforts to assess virus viability.” This is further emphasized at later points that only the presence of RNA was tested not actual infectious material. On page 5 about a third of the way down the page referencing a separate study it is noted “The percentage of positive samples from each room ranged from 50% to 100%. There was no clear correlation between severity of illness, cough, or fever…” And when I combine that with this from page 6 just a few lines down “.. a direct source of SARS-CoV-2 may be due to resuspension of virus-laden aerosol from the surface of medical staff protective apparel during removal.”

When I look at all of that information together I get the impression that they aren’t actually sure how the samples are getting into the air and can’t account for the variances in concentration. So even though they have found evidence of viral material on air vents or aerosolized outside of the room it is not any kind of proof that this was transmitted simply by talking or even coughing.

One last piece of relevant information is further down on page 6 under C. Caveats, Needs in the second and third Sentences, “Although Viral RNA was detected in many environmental samples across various studies, infectivity is not known. It is important to note that there are no available data to our knowledge that speak to the possible linkage between the presence of environmental viral RNA or even infectious virus and the risk of transmission from these environmental sites to humans.”

I appreciate all the time and effort the researches are putting into these studies and even the degree to which it is being shared and discussed. Largely what they are saying is they have found evidence and developed the next theories that need to be tested. Perhaps some of these theories need to inform policy or personal decisions about enhancing our social distancing or safety precautions.

I do not think this research warrants the sort of hook that CNN decided to open with “A prestigious scientific panel told the White House Wednesday night that research shows coronavirus can be spread not just by sneezes or coughs, but also just by talking, or possibly even just breathing.”