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Comment by GeekyBear | Hacker News Reader

Scientists spent several years trying to convince the powers that be that Covid spread was airborne.

>In an open letter published today (July 6 2020), 239 scientists from 32 countries urge the World Health Organization and other bodies to address the potential for airborne transmission of the coronavirus. The authors write that a growing body of evidence suggests “beyond any reasonable doubt” that the virus spreads indoors through tiny aerosols—a finding that should be reflected in the WHO’s recommendations.

https://www.the-scientist.com/news-opinion/scientists-urge-c...

How sad that it has taken this long to reach acceptance that you need a mask capable of filtering the air you breathe.

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> Scientists spent several years trying to convince the powers that be that Covid spread was airborne.

Several months, perhaps? The article you link to and the letter it references are both dated July 6 2020. Even now COVID-19 has only existed for a couple of years (not several).

It is impossible for anyone to have spent several years (by July 2020) doing anything relating to a specific virus or the consequential disease 7 months after the first known infection.

The evidence for finding that Covid was airborne was discussed before the letter was written.

The Pacific Princess, where the virus continued to spread between passengers who were locked down in their cabins, was in January 2020, for instance.

Yes, so again, a period of several months, not several years.

Part of it is the pre-Omicron, it took more virus to typically infect people. So the more typical masks helped a lot. Now even a tiny bit can easily infect, so aerosol (as opposed to droplets) was not nearly as big an issue.

Regular cloth masks do not filter virus floating in the air you breathe and they never did.

Here's one of the scientists from President Biden's Covid advisory council being interviewed on PBS last year:

> I have had concerns that date back to april of 2020 about the concept of masking.

Needless to say it's a political hot button beyond anything I've ever seen in public health, and yet at the same time i think we've all done a disservice to the public.

When you actually look at face cloth coverings, those cloth pieces of hang over your face, they actually only have very limited impact in reducing the amount of virus that you inhale in or exhale out.

In fact in studies that have been done show that if an individual might get infected within 15 minutes in a room, by time and concentration of the virus in the room, add a face cloth covering you only get about five more minutes of protection.

I've been really disappointed with my colleagues in public health for not being more clear about what can masking does or does not do.

On the other hand if you use the n95 respirators and fit them tight to your face, you can actually spend 25 hours in that same room and still be protected.

https://www.pbs.org/wnet/amanpour-and-company/video/do-masks...

A 33% efficacy improvement seems great to me for such a simple, easy, cheap, and accessible countermeasure.

So when you send a child to school for the day, they are only going to be there five minutes?

>Fitted particle-filtering masks like N95s are up to 75 times more effective at preventing infection with COVID-19 than surgical masks, according to a study published recently in the Proceedings of the National Academy of Sciences.

https://www.axios.com/n95-mask-protection-covid-958039c9-07f...

How in the world did you get to this retort from my statement?

My child is too young to go to school. If my child was school age I'd likely unenroll this semester. If that somehow were not an option I'd send with an n95. Are you satisfied?

Personally I think cloth masks are worthless for anything but the most casual exposure to the virus, and then for it to maintain any reasonable protective effect, you would need to remove and dispose of the mask as those luckily trapped virus particles can dislodge and infect. Continuing to wear a cloth mask that has accumulated virus particles in it just turns a chance casual exposure into a long term one.

So one, you would need to know you were casually exposed (most folks don’t) And two, you would need to have a pretty good supply of masks carried with you at all times to replenish on every exposure.

I think you are likely making up the exposure risk based on "conventional" wisdom. I imagine the actual efficacy gain of a simple cloth mask has nothing to do with "trapping" virus particles. My guess for where the actual efficacy comes from is

1) not being able to touch your mucus membranes with your hands anymore

2) limiting the amount of air circulating near your face by limiting induced currents due to your inhale/exhale cycle

If I'm right, your conclusions about gaining the effectiveness of a simple cloth mask are completely off base.

Definitely curious if you happen to know of a study that looks at the mechanisms of protection for a non filtering mask!

Sure its CW, but my point was that any possible blocking of virus particles would be completely incidental/accidental, and because the mask is not effective at all at stopping those particles due to their size and weave of the cloth, anything incidentally blocked would not necessarily be blocked again but could still pass through even if you were no longer exposed to the initial source.

If you can point me to a peer reviewed study extolling the virtues of cloth masking, I’ll read it. But pretty much all of the positive masking studies with any real statistical benefit of protection seem to be centered around n95 or surgical masks—worn correctly and disposed of after one use.

You can't have it both ways. Either simple cloth is not good at filtering the virus, and therefore we shouldn't care about retransmit risk from "trapped" virus. Or it is good at blocking them (like an n95) and you can start thinking/caring about second order effects like retransmission of trapped virus.

I don't need a peer review study to tell me to ignore the epsilon squared term when the epsilon term is already being argued to be marginal. If an article comes through claiming the inverse, that is surprising and worth communicating at large.

No, I am not having it both ways. I don’t think cloth masks are effective at all. I’m responding to the “cloth masks are 5-33% effective” for incidental exposure commentary as a positive aspect of cloth masking. It’s a red herring that creates a false sense of security.

My point is that if a cloth mask is only partially effective for an incidental exposure than it must have been somewhat effective at a given moment, but due to virus size and cloth weaving…every moment that the particle didn’t reach your nasal passages due to that momentary chance then that virus still has a 67%-95% of entering you and infecting you every moment it is near you. So any incidental exposure becomes non-incidental.

I appreciate you clarifying your reasoning. I think it's straight up crazy/magical reasoning. But to be honest I don't have much more confidence in my own conjectures on this matter.

I don’t see what’s all that magical about assuming something that is 33% effective at any given moment would not all of a sudden become 100% effective at every other moment. But perhaps when you roll a die the same number appears every time. I just know that when I roll a die I generally have a 1/6 chance that my first number comes up again on every roll I try.

Perhaps randomness and chance is magical. I always thought it wasn’t.

Perhaps it's a failure in this communication mode. It seems to be that you've argued yourself down a garden path. From my understanding your statements are

A) using incorrect concepts (moment in time? A 15 minute infection window turns into a 20 minute infection window)

B) simply irrelevant. Unless you can provide evidence to the contrary, cloth masks aren't trapping any relevant amount of virus

Then you haven’t understood a thing. Have a good day.

Many people still seem to think that it is transmitted on surfaces. Not instead of airborne, but additionally.

And I don't mean experts or lawmakers (that I know of), I mean in my area of the US, grocery stores and gas stations (sometimes) have signs saying put a plastic bag or gloves on your hands.

The initial advice was all based on the theory that Covid had a droplet based spread: Wear a cloth mask to catch large droplets before they spread. Stay six feet apart, because large droplets fall to the ground within that distance. Use hand sanitizer and disinfect surfaces droplets might fall on. Put up sneeze guards at registers to protect the cashiers.

However, once you know the virus is fully airborne, you can focus on different things, like improving indoor ventilation in public spaces so you are constantly exchanging inside air for outside air.

We have HVAC systems that will help recover the ac/heat when you do this.

> How sad that it has taken this long to reach acceptance that you need a mask capable of filtering the air you breathe.

A lot of us were lied to about masks at the beginning of this, so it's not terribly surprising.

Unfortunately, it got politicized, at which point facts no longer matter.

When we thought that Covid spread by the large droplets you spray out when you cough or sneeze, wearing a cloth mask to catch those droplets before they landed on people or surfaces that people will touch made sense.

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