I could not agree more with Dr. Morris and his excellent, balanced thread.

I like the visualization but I have the same concerns with this piece. It makes an assumption that aerosol transmission is the overwhelming form of transmission. https://twitter.com/ASPphysician/status/1321798685991186434

And relies on the personal opinion of scientists who are experienced in aerosols, but no background in epidemiology or virology or any kind of infectious disease transmission rather than hard data.

This letter in Science? I was originally going to be a co-author but I removed my name because it overstated—without evidence—the dominance of aerosol transmission and continued to use the confusing term "airborne." So did @SaskiaPopescu. https://twitter.com/ASPphysician/status/1321798688138616832?s=20

The model to estimate transmission risk featured here is flawed and not supported by epidemiological evidence. Dr. Morris includes this example, where transmission is estimated at 83%: https://twitter.com/ASPphysician/status/1321798692274233344?s=20

Then he shows data that secondary household attack rate isn't anywhere near that. This strongly suggests that proximal transmission (which can be droplet/contact or inhalation) is what is occurring in the real world rather than overwhelming aerosol spread. https://twitter.com/ASPphysician/status/1321798697609355264?s=20

In other words, this estimator uses a model that is predicated on an assumption made by aerosol scientists but is not actually supported by the epidemiologic data. And that's good news, because if it were ALL aerosols, there would be even more cases than there are now.

So yes, aerosols are important. Yes, ventilation is important, too. We should implement measures to reduce exposure by inhalation, but not at the expense of reducing risk of other modes of transmission.

That means:
-Wear masks
-Limit proximity and duration of contact
-Avoid crowds
-Avoid enclosed spaces
-Physically distance
-Ventilate if possible
-Wash hands
-Disinfect high-touch surfaces
-Don't rely on this pretty tool to estimate overall transmission risks.