Thread by @federicolois

1/ Let's look at this paper: "Influenza Virus Aerosols in the Air and Their Infectiousness" from 2014 (we cannot claim this was unknown). We know now that we have a new kid on the block now, ready to challenge Influenza for supremacy in the transmissibility metric.

2/ So there were these guys that actually infected people with Influenza to measure how infectious it was. That is a 'challenge study', this is no 'model' this is actual humans. And they found, that with as much as 3000 copies you get it.

3/ Another study actually measured how many particles an adult would inhale in 1 hour given the concentrations found on a health center, a day-care center, and airplanes.

4/ But here comes the interesting part. So 99% of total viral particles were found where you think? Of course, those that have been following for a long time knows... Aerosols. And those guys are actually quite difficult to stop and decay.

5/ Oopsie. Are these guys saying that >99% of the exhaled particles are aerosol? You know those things that escape and are known as "the plume" when laser imaging is used to see how particles behave after someone breathes or worse "coughs".

6/ Small particles are bad, and the reason why is because they can escape the vortex it is created for the purpose of capturing 'impurities' and 'unfriendly guests' that happen to be inhaled. So they can travel straight to the pulmonary alveoli.

7/ Good thing about biology is while you will always get bitten by something you thought you knew, usually the behavior rhymes. Where did I saw something like this? Ohhhh. Yes.

https://twitter.com/federicolois/status/1358250794655621120

8/ At this point many would be tempted to just call it a day.

https://twitter.com/xkcdComic/status/1228402773722427392

But you know me better ;)

9/ This part is interesting, breathing not coughing, or sneezing events are the actual high contributors. Who would have thought that?

10/ So now let's switch to another interesting paper "A cluster-randomized trial of cloth masks compared with medical masks in healthcare workers", this one is pretty good because you know they conclude that masks work.

11/ I won't bore you with the details so we are going to go straight to Figure 2. And without further ado, there it is... And here comes the poll.

12/ In which order of importance this graph is ordered?

13/ Weaker to Stricter. So the criteria to enter into the clinical respiratory illness (Left) is far weaker than actually having isolated and confirmed which 'virus' on the Right.

14/ The control group here is interesting though. By their own admission, it was a do what you want kind of thing, but interestingly while most used one or the other, the compliance is half of the other 2. So in a sense that is normal pre-pandemic behavior at hospitals.

15/ Now to the important stuff. What happens when something consistently performs worse than the control group?

16/ Correct (whatever you had responded in there). The interesting thing here is that even the do whatever group (you know the crazy ones, the misfits, the rebels, the troublemakers) are no worse (and in fact are better) than the cloth masks guys.

17/ One can also point out that we are doing all this fuzz for that whatever 0.5% difference in the stricter category (well within the margin of error) we are probably looking to optimize something that is impactless. I would be far more convinced if it shows a ZERO.

18/ But again you know, biology tends to bite those too sure in the ass, but nonetheless it often rhymes.

https://twitter.com/federicolois/status/1357919000945184768

19/
References:
pubmed.ncbi.nlm.nih.gov/25197278/
academic.oup.com/cid/article/71…
ncbi.nlm.nih.gov/pmc/articles/P…