Here's one of the scientists on President Biden's Covid advisory council being interviewed on PBS.
TLDR: To get the sort of protection people imagine that cloth masks provide, you would need to be wearing an n95 mask, tightly fitted to your face so no air leaks in through the sides.
But what's the actual effectiveness of most people wearing their normal cloth masks?
It doesn't have to personally protect you at high effectiveness from getting infected to reduce spread at a population level.
Even a 50% reduction in spread is huge in a population. Maybe we aren't getting that with masks, but it's not a binary "you are protected"/"you are not protected" problem.
>Needless to say, masking is political hot button beyond anything I've ever seen in public health.
At the same time i think we've all done a disservice to the public.
When you actually look at face cloth coverings, they actually only have very limited impact in reducing the amount of virus that you inhale in or exhale out.
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 can do or 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.
The bottom line though is by telling people that in fact just putting a face cloth covering on is going to protect you is simply not true.
I'm just asking if we have info on population spread effects for masks / no masks.
"Masks won't protect you" isn't an answer to that question. I don't wear a mask when requested by local guidelines or businesses as some kind of guarantee that I don't get COVID.
And yes, having kids not all go to school and then return to their families on a daily basis would probably have a much bigger affect on community spread. But if we can't get political will for masks or vaccinations then I don't know where we're going to find it for another round of kids staying home.
>Amid COVID-19 pandemic, flu has disappeared in the US
NEW YORK (AP) — February is usually the peak of flu season, with doctors’ offices and hospitals packed with suffering patients. But not this year.
Nationally, “this is the lowest flu season we’ve had on record,” according to a surveillance system that is about 25 years old, said Lynnette Brammer of the U.S. Centers for Disease Control and Prevention.
Even a 50% reduction in spread is huge in a population. Maybe we aren't getting that with masks, but it's not a binary "you are protected"/"you are not protected" problem.
A 50% reduction and we still all get covid. It is actually binary -- either we have a realistic and obtainable plan for zero-covid (which we do not) or everyone gets exposed to covid eventually.
A 50% reduction in spread might be helpful in certain areas where the hospitals are on the verge of being overwhelmed (in which case just close the schools for a few weeks), but in the United States there are a lot of mask mandates in schools being pushed in areas where the hospitals are not under any significant pressure. That is nonsense.
One issue is that with exponential curves it's often difficult to make these big policy changes as local conditions change.
Sure in an ideal world as soon as hospitalizations or case rates went above some metric we'd introduce stricter local procedures, hopefully fast enough that the wave of hospitalizations 1-2 weeks later isn't too bad.
But so far it seems like we're too slow on that. Things get bad, then we start changing our behavior. Time matters and it's not binary. That's been the whole principle of managing this thing in the US at the beginning. If you let the spike get too big too quickly then it gets bad before we can take corrective action.
And how would we even manage changing these guidelines on a week-by-week basis in every zip code? How do you even disseminate that information to all businesses, citizens, parents?
Of course I don't think all restrictions make sense in all places, nor do I want them to go on forever. Vaccinations for a large majority of eligible individuals would go a long way to reducing spread and hospitalization load.
In theory we are trying to bide time until we get there (manageable COVID, not zero COVID) but in the US at least we're not heading towards "large majority" very quickly, and we are still having those exponential local spikes.
Something like 30% (of expelled particles) when we’re talking about face-to-face contact for a few minutes.
Probably pretty close to zero when we’re talking about being in a classroom with 30 other kids for a few hours. The mask protects against things going straight ahead, not against slowly filling up a room with aerosols.
I guess masking up might mean everyone gets slowly infected over the course of days though (through aerosols), instead of getting a full dose of virus straight in the face. I presume that affects the severity of the subsequent disease.
I appreciate the simplicity of the message to mask up, since it’s almost certainly better than nothing, but it’s no panacea.
Masks is too broad of a term as being used. There are OSHA environments where proper N95-type masks can protect you from aerosol risks for 8 hours a day.
The likelihood that a cloth mask can do that in a classroom however…
Best mitigator would be good HEPA room air purifiers, ideally multiple per classroom.
> Best mitigator would be good HEPA room air purifiers, ideally multiple per classroom.
They can be too loud to run while class is in session, especially if they move enough air to be worth a damn. Double-especially if you're also masked (so speaking is already a bit muffled).
I've got a couple of Coway HEPA purifiers, and they can be quiet enough for a classroom. At low speeds, the closest to inaudible that I've ever heard, and at higher speeds a very even and tolerable white/brown noise.
I'm sure some that are good-enough and not loud exist, and some classrooms probably have them, but I can also say for a fact that some schools that have managed to get ahold of good purifiers for every classroom haven't also managed to get ahold of quiet good purifiers, which is why those schools only run them part of the time. It's another hurdle to the solution of "just filter the air", which isn't per se a bad idea—but, whoever's procuring them must think to look into the noise when choosing which to buy, must have the budget to buy quiet ones that move as much air as appropriately-effective louder models (I assume there's a cost premium for "quiet and also effective"), and if someone's already bought purifiers and they're too loud, you're out of luck on getting anyone to pony up cash for a second set of (maybe even more expensive) purifiers.
We seem to be forgetting something here: the aerosols we are protecting from are from other peoples nose and mouth, which are covered by a cloth mask which vastly reduces how much makes it into the air.
There is no "best" here, mitigations all mitigate different things and work together to provide a safer environment.
> which are covered by a cloth mask which vastly reduces how much makes it into the air
Where do you think the extra air goes?
It still makes it into the air, just in different directions. Some of the viral particles are probably caught in the mask, but I’m not sure how much of the total we can count on.
Edit: Allow me to clarify - the research everyone is citing that says masking is effective in teachers and ineffective in students (the 37% number) predates both the delta variant and widespread infection in Southern states. Further, masking is understood etiologically as a prevention method and has been used successfully in other outbreaks and in other countries. Clinicians and policy makers as a rule work with incomplete data in an emerging situation, so unequivocally stating that masking kids in schools doesn't help is a very bad misrepresentation of both the data/research and the implications to policy.
When a novel situation presents itself, sometimes we do not have all of data we would like and clinicians have to make judgement calls to the best of their knowledge.
We may not have trials or studies (these things take time) to back a very certain and/or specific claim such as "do masks prevent the spread of Covid 19?" What we do have, is fundamental knowledge and common sense and so typically, in a clinical setting we ask these questions when any new situation arises (as it happens often in medicine):
- Does this reccomendation cause more harm than good?
- is there even a slight chance that this clinical decision would increase the percentage chance of survival?
- is it worth the inconvenience it could cause?
This is called Clinical Reasoning. Thinking critically and clinically is a core tenet of the field.
I don't disagree with anything you said, and I'm certainlynot an anti-masker, but was skeptical of the parent claim which seems to be
"Research shoes masks are still effective even when spending the whole day in the same room"
I'm not aware of any evidence that this is the case and I worry that people are putting too much stake in masks when really social distancing is much more effective than masks ever will be.
Keep in mind the initial dose is highly relevant to the impact of the virus in your body. There's a big difference between getting a single virus, enough to cause an infection, and enough to be highly overwhelmed before your immune system kicks in.
There is no real scientific evidence that disease severity is correlated with initial viral dose. It's a plausible hypothesis but so far due to ethical concerns no one has done the human challenge trials that would be necessary to settle that issue.
This is a common attribute of infections and is really more of a math issue than anything SARS-specific. The bigger the initial dose, the sooner it will get to the impact stage, and the less prepared your immune system will be at that time.
Key paragraph: Between Nov. 16 and Dec. 11, researchers found that infection rates were 37% lower in schools where teachers and staff members were required to wear masks. The difference between schools that did and did not require students to wear masks was not statistically significant.
Many countries in Europe have decided against masking for any students in K-12 schools because it is unclear that the harms outweigh the benefits. The idea there is some "simple" scientific & research consensus on this is wrong.
Is it worth the cost? That’s a different question.
I’m not really opposed to masks in a classroom as a mitigation method, but if people believe it will significantly alter the trajectory of the infections I have a bridge to sell them.
