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Sorry it took a while to respond, I had some family things happening the past couple days that took me away from these fun discussions.

I saw that study and it’s really interesting, but there’s a couple points to be made there. First, the World Health Organization pointed out (https://www.who.int/news-room/commentaries/detail/transmission-of-sars-cov-2-implications-for-infection-prevention-precautions) that this study used a high-powered nebulizer to generate their aerosols, which works significantly differently from humans. They also examined multiple other studies discussing the potential for aerosolized transmission, but detailed examination of both healthcare facility transmission patterns and crowded indoor public place outbreaks have shown no conclusive instances of actual transmission via aerosols. Every single case to date is explainable via respiratory droplet transmission.

Still, the possibility is acknowledged by them and others. The research from around the world continues to support transmission primarily by respiratory droplets.

Another aspect to consider is the basic reproductive number for SARS-CoV-2 (recent estimates put it as likely between 2.2 - 3.8). If you look through the R0 for various diseases, you find they generally fit into rough groupings based on their transmission modes. For viruses that readily infect via aerosols, you typically see an R0 in the 10-18+ range. For respiratory droplet transmission, you can reach up to around 7. For other things like bodily fluids (e.g. Ebola), you can hit up to around 2. Considering SARS-CoV-2’s R0 of 2.2-3.8, it is highly unlikely that aerosolized transmission makes up many (if any) of the actual real world transmission for it. Otherwise, it would be - by far - the worst performing spreader for an aerosolized virus that I could find any documentation on.

So sure, it’s at least theoretically possible there are some cases occurring due to aerosolized SARS-CoV-2, just like with fomites. But it’s highly unlikely that very many actual infections are taking place that way.

that this study used a high-powered nebulizer to generate their aerosols, which works significantly differently from humans.

True, but the point of the study is to look at aerosols specifically, so generating bigger droplets won't help with looking at aerosols. But yes, I do agree that the methodology is not exactly similar to human breathing.

Every single case to date is explainable via respiratory droplet transmission.

And, every case explainable as such, is also explainable by an aerosol vector. The two aren't mutually exclusive, they overlap a lot. Especially from a virus like this, where I've heard that it doesn't take a high viral load to initiate an infection.

Another aspect to consider is the basic reproductive number for SARS-CoV-2. If you look through the R0 for various diseases, you find they generally fit into rough groupings based on their transmission modes... Otherwise, it would be - by far - the worst performing spreader for an aerosolized virus that I could find any documentation on.

True, I haven't looked at that before. But, it's hard to really pin down these numbers during the course of spread, versus looking back at solid information. And, for the supposedly high number of asymptomatic carriers walking around, the R0 might be much higher than people calculate it to be. And of course, taking into account the entire US population ignores that the virus isn't even present at all in every community - R0 is difficult to truly calculate. If 16 people get infected, that could be an R0 of eight - only two people were the source infection for all of them. Or, an R0 of two, as each person infects two others til you hit those 16 people.

And a big indicator towards aerosols and not droplets, is the relatively large spreads in several States in these US where masks were heavily required - stopping droplets is the one thing these masks are actually pretty good at. but aerosols, not so much.