Why aren’t we talking more about airborne transmission? • Hacker News Board

Re: Why aren’t we talking more about airborne transmission?

#161

Post by war1025 » Mon, Aug 03, 2020, 4:57 PM UTC

mensetmanusman wrote: post #125

I am still shocked: months after research has shown that SARS-CoV-2 is airborne stable in aerosol form for over 3 hours, we still aren’t telling the public that room air purifiers are a ‘good thing’ (for making indoor air like outdoor air - in regards to virion density per cubic air volume) The filter technology is essentially the same as in the N95, orders of magnitude more effective than cloth masks. Put these indo…

A thing I really wish would catch on is people actually leaving their windows open to get proper ventilation of their living spaces.

Air purifiers seems like a great idea, but if the outside is the safest place in terms of the virus, bringing the outside in to you seems like a no-brainer.

In general, I'd say outdoor air beats indoor air probably 99 times out of 100.

Re: Why aren’t we talking more about airborne transmission?

#162

Post by clairity » Mon, Aug 03, 2020, 4:58 PM UTC

jennyyang wrote: post #120

jtbayly wrote: post #68

Earlier quoted context omitted.

> we would have to implement extremely strict lockdowns... if we assume that the goal is not to flatten the curve but to completely stop the virus in its tracks. Most people and countries don't have this goal. Edit: To those downvoting, I'll just say that my statement is factual, so argue the facts. Long-term, we want a vaccine, yes. In the meantime, most people and countries are simply not willing to do what it take…

If the virus were truly airborne, which it isn't, then simply walking through an empty room could get you infected. The levels of people getting infected, and subsequently getting hospitalized would be far worse than the worst scenes we saw in Italy and NYC. Lockdowns absolutely would have been mandatory for months upon months. Coronavirus is not by itself a tremendously deadly disease. The problem is how infectious…

thanks for continuing to tease out the nuance. nearly all coverage and discussion of covid is an exercise in frustration, one way or the other.

the unrealistic desire for riskless, surefire mitigations had led us exactly into the ping-ponging uncertainty that such longing tries so strenuously to avoid. it's wreaking havoc on our social and economic lives, let alone politically.

taking into account what we know so far, the best bang-for-buck rule is still "distance (inside), and when you can't, mask.", not shutdown, or mask outside and all the time, or never mask or distance, or business as usual, or wipe down surfaces incessantly, or reconfigure every hvac system.

the simplicity of that one rule belies a lot of understanding packed into it, unfortunately, leading to an unnecessary yearning for more. there isn't more that we ordinary folks can do than that. that's not to say don't be cognizant of the progress we're making, but does suggest we need to stop fretting while we wait for more effective treatments, herd immunity, and/or a vaccine.

Re: Why aren’t we talking more about airborne transmission?

#163

Post by jansan » Mon, Aug 03, 2020, 5:01 PM UTC

mensetmanusman wrote: post #125

I am still shocked: months after research has shown that SARS-CoV-2 is airborne stable in aerosol form for over 3 hours, we still aren’t telling the public that room air purifiers are a ‘good thing’ (for making indoor air like outdoor air - in regards to virion density per cubic air volume) The filter technology is essentially the same as in the N95, orders of magnitude more effective than cloth masks. Put these indo…

Opening the windows more often may also help a lot. This is a very simple method to reduce risk of spreading. It is free and especially useful for places like schools. But I do not think I read about this in mainstream media. It's all about masks and social distancing.

Re: Why aren’t we talking more about airborne transmission?

#164

Post by mensetmanusman » Mon, Aug 03, 2020, 5:05 PM UTC

war1025 wrote: post #161

mensetmanusman wrote: post #125

I am still shocked: months after research has shown that SARS-CoV-2 is airborne stable in aerosol form for over 3 hours, we still aren’t telling the public that room air purifiers are a ‘good thing’ (for making indoor air like outdoor air - in regards to virion density per cubic air volume) The filter technology is essentially the same as in the N95, orders of magnitude more effective than cloth masks. Put these indo…

A thing I really wish would catch on is people actually leaving their windows open to get proper ventilation of their living spaces. Air purifiers seems like a great idea, but if the outside is the safest place in terms of the virus, bringing the outside in to you seems like a no-brainer. In general, I'd say outdoor air beats indoor air probably 99 times out of 100.

It is all about virion particles per cubic meter (similar to how they classify class ## cleanrooms for the semiconductor, but in that case they talk about dust particles).

Outdoor air works through dilution (‘the solution to pollution is dilution’ is the phrase often used).

Indoor air being purified is often much cleaner than outdoor air (assuming CO2 levels are not of any concern), this is especially true during wildfire season.

If you purchase a PM2.5 sensor and put it in your kitchen while you make toast, you will be shocked. (do this with and without an air purifier near by to be calmed :))

Re: Why aren’t we talking more about airborne transmission?

#165

Post by SkyPuncher » Mon, Aug 03, 2020, 5:05 PM UTC

pwned1 wrote: post #137

SkyPuncher wrote: post #130

Earlier quoted context omitted.

> It was clear from the very beginning that transmission was airborne. To me the only thing that was clear was the definition of airborne is not standard. By strict definition, COVID is not airborne since it seems to require a host material (e.g. water droplet). This is in contrast to measles which individual virus particles can survive without a host material. Practically speaking though, COVID seems to be able to s…

Just to be pedantic. SARS-CoV-2 is the virus, Covid is the disease. The same as HIV vs AIDS.

I'm aware. Covid is half as long and everyone knows what I'm talking about.

HIV/AIDS is a bit more important because the disease can lag the infection by a large period.

Re: Why aren’t we talking more about airborne transmission?

#166

Post by mensetmanusman » Mon, Aug 03, 2020, 5:06 PM UTC

jansan wrote: post #163

mensetmanusman wrote: post #125

I am still shocked: months after research has shown that SARS-CoV-2 is airborne stable in aerosol form for over 3 hours, we still aren’t telling the public that room air purifiers are a ‘good thing’ (for making indoor air like outdoor air - in regards to virion density per cubic air volume) The filter technology is essentially the same as in the N95, orders of magnitude more effective than cloth masks. Put these indo…

Opening the windows more often may also help a lot. This is a very simple method to reduce risk of spreading. It is free and especially useful for places like schools. But I do not think I read about this in mainstream media. It's all about masks and social distancing.

I am concerned about winter, because we have to prep now for that.

Re: Why aren’t we talking more about airborne transmission?

#167

Post by guscost » Mon, Aug 03, 2020, 5:10 PM UTC

mensetmanusman wrote: post #132

jennyyang wrote: post #120

Earlier quoted context omitted.

If the virus were truly airborne, which it isn't, then simply walking through an empty room could get you infected. The levels of people getting infected, and subsequently getting hospitalized would be far worse than the worst scenes we saw in Italy and NYC. Lockdowns absolutely would have been mandatory for months upon months. Coronavirus is not by itself a tremendously deadly disease. The problem is how infectious…

Um.. it is airborne, that is why there are multiple super-spreader events that can’t be explained by someone interacting within 3-6 feet for 10 minutes. (e.g. cases of 1 to 100, 1:500 case reported as well). If you walked into an empty hospital room that was just used with high air-virion density, you could get infected, that is why they decontaminate with the equipment you see. I think the main reason this isn’t bei…

I would bet that you are right, but it is still a controversial opinion, and droplet transmission is probably still a major factor. Plenty of research supports the claim, although some studies conclude that it is only significant when the spreader has a high viral load:

https://www.nature.com/articles/s41598-020-69286-3

https://jamanetwork.com/journals/jamanetworkopen/fullarticle...

https://www.medrxiv.org/content/10.1101/2020.07.16.20155572v...

https://www.medrxiv.org/content/10.1101/2020.07.13.20153049v...

Re: Why aren’t we talking more about airborne transmission?

#168

Post by CogentHedgehog » Mon, Aug 03, 2020, 5:11 PM UTC

misanthropian00 wrote: post #65

CogentHedgehog wrote: post #31

Short-distance aerosol transmission changes things a bit: * Social distancing isn't enough to guarantee safety in indoors spaces: bad news for bars, clubs, gyms, concerts, and restaurants * Outdoors spaces are probably safer than we previously thought * Indoor mask-wearing becomes CRITICAL in public spaces * Indoor ventilation becomes extra important, using fresh air from outside or filtered/UV-sanitized air * Indoor…

More emphasis on better masks that actually might prevent aerosol transmission and less emphasis on 6 foot distancing because such things matter little under aerosol conditions where air flow patterns dominate transmission. Also much more emphasis on outdoor vs indoor activities. So no it is not really the same guidance.

Your claims do not reflect what the article and the evidence it cites show. To quote:

> Cowling told me that it’s better to call these “short-range aerosols,” as that communicates the nature of the threat more accurately: Most of these particles are concentrated around the infected person, but, under the right circumstances, they can accumulate and get around.

This is the precise opposite of your claim that 6 foot distancing would "matter little under aerosol conditions where air flow patterns dominate transmission." AT NO POINT does the article indicate that droplets are irrelevant. We know they are the key factor in person-to-person transmission. But we also now have evidence that short-range aerosols also play a role, especially in superspreading events.

The evidence is VERY clear that risks are highest in close proximity to infected individuals.

I would encourage you to take another look at the article and read closely.

Re: Why aren’t we talking more about airborne transmission?

#169

Post by CogentHedgehog » Mon, Aug 03, 2020, 5:12 PM UTC

DanBC wrote: post #46

CogentHedgehog wrote: post #31

Short-distance aerosol transmission changes things a bit: * Social distancing isn't enough to guarantee safety in indoors spaces: bad news for bars, clubs, gyms, concerts, and restaurants * Outdoors spaces are probably safer than we previously thought * Indoor mask-wearing becomes CRITICAL in public spaces * Indoor ventilation becomes extra important, using fresh air from outside or filtered/UV-sanitized air * Indoor…

> Indoor mask-wearing becomes CRITICAL in public spaces Mask wearing provides minimal benefits against droplet transmission, but they do nothing at all for small droplet aerosol transmission.

That's actually the opposite of what the evidence shows. Masks - even crappy ones, with poor mask protocol - dramatically cut infections https://arstechnica.com/science/2020/06/modeling-the-impact-...

Citation: https://www.healthaffairs.org/doi/10.1377/hlthaff.2020.00818

Remember: even if a mask doesn't effectively filter out very small particles, it still restricts the velocity of air passing through it. This means aerosolized particles will not travel as far.

Re: Why aren’t we talking more about airborne transmission?

#170

Post by misanthropian00 » Mon, Aug 03, 2020, 5:14 PM UTC

ghaff wrote: post #66

sigstoat wrote: post #51

Earlier quoted context omitted.

> Talking about airborne transmission, though? The kind of masks that can protect against that are hard to come by. Not to mention that the virus could enter via the fluid of the eyes (not trying to add conspiracy here, just trying to make a point about the difficult reality of preventing infection [0]). Bio-rated goggles and N95+ rated masks are more than we can expect from a public that's making face masks out of b…

I think that's what the parent was saying. The widespread wearing of just about any face covering seems to help on net even if it's probably >50% about protecting other people. Even if higher-level protective gear were readily available, most people wouldn't wear for any length of time and it wouldn't be fitted properly. So just wear something seems to be the most reasonable advice for the general population.

Do you have proof that people would not wear better protection and that it would be ineffective even if they did to due fit issues? Or are you just making an assumption?

The fact that N95 masks were and still are selling for such high prices seems to be evidence against this view. I assume this view is most popular among Americans because Americans seem to represent the majority of anti-maskers.

Where I live everyone wears a mask but very few people wear N95 masks simply because they are more expensive and hard to find. If COVID is short range aerosol infectious as some evidence suggests greater N95 mask availability and usage may affect infection rates at least outside of the US. How significant a difference this might make is simply unknown at this time.