If you’re shedding the virus (being infectious, possibly before showing outward symptoms) and you’re wearing a mask, probably the virus is less likely to get to people around you in a supermarket or in public transportation? Therefore, masks work at least a bit? Isn’t that obvious? What am I missing?
Mechanistic explanations are good for priors, but don’t replace, much less refute, empirical evidence. If we see that there is ~0% impact in RCTs, the fact that we know better because it “must” decrease transmission isn’t relevant. And the mechanistic model could be wrong in many ways. For example, maybe people wear masks too poorly to matter (they do!) Maybe masks only help if people never take them off to blow their nose, or scratch it, or similar (they do all those things, too.)
And we see that even according to the paper, the impact is pretty small, so it mostly refutes the claim made by the mechanistic model you propose—the impact just isn’t that big, for various reasons. Which would imply that there is no way to know if it’s materially above 0%.
In fact, I think it’s likely that the impact is non-trivial in reducing transmission, but the OP is right that we don’t have strong evidence.
Right, I agree with all that. I wanted to express that my prior is high for masks working at least a bit. I find it weird to write as though the burden of proof is on finding solid evidence that they do work. I wouldn’t have commented if the OP had titled the post “We still can’t be certain if masks work.”
There are two separate questions: (1) Should you wear a mask. (2) Should you feel save when you wear a mask and are with other people that wear a mask.
When it comes to (1) the evidence that you need is more lower then for (2).
It might be that as you exhale more and more viruses get into the mask and while the mask filters, when you let clean air go through the mask filled with viruses that air will partly be filled with viruses, so over the span at of a few minutes you are still putting out 80% or virus particles.
Especially, with clothing masks that are not designed to actually do good filtering.
Mask quite clearly prevent droplets but when it comes to aerosol the case is less well (I have heard the hypothesis is that this is partly the reason why the WHO still hasn’t accepted that COVID-19 transmits via aerosol.
In the thread model of aerosol transmission a bunch of good airfilters might do more then a clothing mask.
If you’re shedding the virus (being infectious, possibly before showing outward symptoms) and you’re wearing a mask, probably the virus is less likely to get to people around you in a supermarket or in public transportation? Therefore, masks work at least a bit? Isn’t that obvious? What am I missing?
Mechanistic explanations are good for priors, but don’t replace, much less refute, empirical evidence. If we see that there is ~0% impact in RCTs, the fact that we know better because it “must” decrease transmission isn’t relevant. And the mechanistic model could be wrong in many ways. For example, maybe people wear masks too poorly to matter (they do!) Maybe masks only help if people never take them off to blow their nose, or scratch it, or similar (they do all those things, too.)
And we see that even according to the paper, the impact is pretty small, so it mostly refutes the claim made by the mechanistic model you propose—the impact just isn’t that big, for various reasons. Which would imply that there is no way to know if it’s materially above 0%.
In fact, I think it’s likely that the impact is non-trivial in reducing transmission, but the OP is right that we don’t have strong evidence.
Right, I agree with all that. I wanted to express that my prior is high for masks working at least a bit. I find it weird to write as though the burden of proof is on finding solid evidence that they do work. I wouldn’t have commented if the OP had titled the post “We still can’t be certain if masks work.”
There are two separate questions: (1) Should you wear a mask. (2) Should you feel save when you wear a mask and are with other people that wear a mask.
When it comes to (1) the evidence that you need is more lower then for (2).
Agreement reached!
It might be that as you exhale more and more viruses get into the mask and while the mask filters, when you let clean air go through the mask filled with viruses that air will partly be filled with viruses, so over the span at of a few minutes you are still putting out 80% or virus particles.
Especially, with clothing masks that are not designed to actually do good filtering.
Mask quite clearly prevent droplets but when it comes to aerosol the case is less well (I have heard the hypothesis is that this is partly the reason why the WHO still hasn’t accepted that COVID-19 transmits via aerosol.
In the thread model of aerosol transmission a bunch of good airfilters might do more then a clothing mask.