Put a water hose on mist and spray someone with it. Then put a cloth over the nozzle and try to spray them. It's self evident yet people just could not grasp it.
https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD...
https://jamanetwork.com/journals/jamanetworkopen/article-abs...
When the medical field phases out masks because they "have no benefit" I will believe that masking was useless. Also keep in the mind that the primary reason for studies showing masks not working is that people don't wear it correctly or at all.
That's just one RCT. The Cochrane meta-analysis looked at a bunch of them.
>When the medical field phases out masks because they "have no benefit" I will believe that masking was useless.
You're putting the cart before the horse. In an ideal world, guidelines for the medical field are based on scientific evidence. But there's always a delay.
You better consult the scientific evidence to make up your mind.
When it comes to covid and masking, policymakers will wait as long as possible before aknowledging the evidence, because they know the public hasn't forgotten the draconian masking of school kids yet.
It is an extraordinary claim that wearing a mask properly does not reduce transmission of viral particles. You'll need to come up with a physical basis for this unintuitive hypothesis if you want to be taken seriously. Then you can point to studies whose results are explained by that hypothesis.
I'm not trying to prove anything. I just rely on the judgement of domain experts.
In this thread I cited Cochrane, The Lancet, SciAm and Science Magazine. If you have more reputable sources, please share them here.
>You'll need to come up with a physical basis for this unintuitive hypothesis if you want to be taken seriously.
It's only unintuitive if you stick to the droplet model. SARS-CoV-2 however spreads like smoke through the air, as I documented already extensively in this post:
SARS-CoV-2 is an aerosolized virus that can spread long distances through air ducts, and hang in rooms for long periods. This was known since the Diamond Princess was put into lockdown and COVID cases appeared randomly throughout the ship anyway, way back in 2020. The only possible explanation for this was transfer via the ship's air circulation system. It's as expected also because the same thing was observed with SARS-1 in Hong Kong.
It may also spread via droplets, but that doesn't mean it's the dominant path or even important at all.
Incorrect models of how this whole thing works are exactly why none of the predictions coming out of epidemiology were correct (or even close). If you think the dynamics of COVID are "self evident to the point of being axiomatic" you'll have to explain why nobody was able to correctly predict what it'd do next.
--> May 2020: "How Coronavirus Spreads through the Air: What We Know So Far"
https://www.scientificamerican.com/article/how-coronavirus-s...
>For months, the U.S. Centers for Disease Control and Prevention and the World Health Organization have maintained that the novel coronavirus is primarily spread by droplets from someone who is coughing, sneezing or even talking within a few feet away. But anecdotal reports hint that it could be transmissible through particles suspended in the air (so-called "aerosol transmission"). And the WHO recently reversed its guidance to say that such transmission, particularly in “indoor locations where there are crowded and inadequately ventilated spaces where infected persons spend long periods of time with others, cannot be ruled out.”
>Even if aerosols do not travel farther than most droplets, the oft-touted “six-foot rule” for social distancing may depend on the circumstances, Cowling says. If there is a fan or air conditioner, infectious aerosols (or even droplets, as was suspected in the case of that restaurant in China) could potentially sicken someone farther away who is downwind.
--> October 2020: "Airborne transmission of SARS-CoV-2"
https://www.science.org/doi/10.1126/science.abf0521
>Viruses in droplets (larger than 100 µm) typically fall to the ground in seconds within 2 m of the source and can be sprayed like tiny cannonballs onto nearby individuals. Because of their limited travel range, physical distancing reduces exposure to these droplets. Viruses in aerosols (smaller than 100 µm) can remain suspended in the air for many seconds to hours, like smoke, and be inhaled. They are highly concentrated near an infected person, so they can infect people most easily in close proximity. But aerosols containing infectious virus (2) can also travel more than 2 m and accumulate in poorly ventilated indoor air, leading to superspreading events (3).
>Individuals with COVID-19, many of whom have no symptoms, release thousands of virus-laden aerosols and far fewer droplets when breathing and talking (4–6). Thus, one is far more likely to inhale aerosols than be sprayed by a droplet (7), and so the balance of attention must be shifted to protecting against airborne transmission. In addition to existing mandates of mask-wearing, social distancing, and hygiene efforts, we urge public health officials to add clear guidance about the importance of moving activities outdoors, improving indoor air using ventilation and filtration, and improving protection for high-risk workers (8).
--> May, 2021: "Ten scientific reasons in support of airborne transmission of SARS-CoV-2"
https://www.thelancet.com/article/S0140-6736(21)00869-2/full...
> First, superspreading events account for substantial SARS-CoV-2 transmission; indeed, such events may be the pandemic's primary drivers. [...]
> Second, long-range transmission of SARS-CoV-2 between people in adjacent rooms but never in each other's presence has been documented in quarantine hotels. [...]
> Third, asymptomatic or presymptomatic transmission of SARS-CoV-2 from people who are not coughing or sneezing is likely to account for at least a third, and perhaps up to 59%, of all transmission globally and is a key way SARS-CoV-2 has spread around the world [...]
> Fourth, transmission of SARS-CoV-2 is higher indoors than outdoors and is substantially reduced by indoor ventilation.5 Both observations support a predominantly airborne route of transmission.
> Fifth, nosocomial infections have been documented in health-care organisations, where there have been strict contact-and-droplet precautions and use of personal protective equipment (PPE) designed to protect against droplet but not aerosol exposure.
> Sixth, viable SARS-CoV-2 has been detected in the air. In laboratory experiments, SARS-CoV-2 stayed infectious in the air for up to 3 h with a half-life of 1·1 h. [...]
> Seventh, SARS-CoV-2 has been identified in air filters and building ducts in hospitals with COVID-19 patients; such locations could be reached only by aerosols.
> Eighth, studies involving infected caged animals that were connected to separately caged uninfected animals via an air duct have shown transmission of SARS-CoV-2 that can be adequately explained only by aerosols.
> Ninth, no study to our knowledge has provided strong or consistent evidence to refute the hypothesis of airborne SARS-CoV-2 transmission. [...]
> Tenth, there is limited evidence to support other dominant routes of transmission—ie, respiratory droplet or fomite. [...]
But I don't get your reply at all, wtallis. "the next few paragraphs should be about backing that claim up with convincing evidence and explanations" - which is what the stuff about the Diamond Princess, SARS-1 and Hong Kong was about? Evidence and explanations for why the droplet model was wrong. Do you see that? The connection is that the claim exposure as simple as inverse square law on distance assumes no aerosol transmission, which is incorrect.
It's hard not to feel that if people didn't keep flagging these kinds of discussions off the front pages, the wider HN community would be aware of all these basic facts which as the sibling post points out, is actually not controversial and hasn't been for years. HN is supposed to be about intellectual curiousity but the aggressive flagging behavior talked about by others in this thread means that too many posters here are stuck in a timewarp where it's still Jan 2020.
In reply to a comment about the inverse square law, you replied with arguments about droplet vs aerosol when neither concept was mentioned in the comment you were replying to. Simply put, your argument was unsound; it lacked any connection between the concepts in your comment and the concepts in the parent comment. As written, it falls somewhere between a non-sequitur and a straw-man.
When your conclusions are correct, such unsoundness is usually easy to rectify; you've now made it at least halfway there by implying that the inverse square law applies to droplet transmission but not aerosol transmission. You now only need to reinforce that new claim with evidence to complete the originally broken chain of reasoning and have a convincing argument.
Even when you are right, you still have a responsibility to make your point using complete and coherent reasoning. I routinely downvote people whose conclusions I agree with when their explanations or justifications are clearly deficient and overreaching and don't come close to proving their point. I flag such comments when it looks like the poster is being disingenuous or displaying egregious intellectual laziness. Because discussions here are meant to be thoughtful and substantive, and you don't accomplish that by regurgitating talking points without even re-writing them to fit appropriately into the context of the discussion. Bad arguments are always bad comments for HN.
(Not having researched the droplet vs aerosol issue myself, my suspicion is that both are likely subject to distance falloff that is at least quadratic, but that the constant factors are so wildly different that effective "social distancing" for aerosol transmission would require distances that do not fit into most indoor spaces, and consequently aerosol transmission in confined indoor spaces can result in aerosol concentration becoming fairly uniform instead of maintaining a strong gradient. But that's rather more reading between the lines than you can reasonably demand from people.)
The evidence for this was referenced in my first post when I mentioned the Diamond Princess. Aerosol transmission isn't even slightly governed by inverse square law of distance from the source. It's fundamentally about air currents, which are non-linear and governed by things like ducts, walls, heat convection and even (in the case of SARS-1) the wind between buildings. You can't model this as a simple linear distance function, and this was made clear when I said that cases on the DP occurred a random throughout the ship.
> I routinely downvote people whose conclusions I agree with when their explanations or justifications are clearly deficient
Don't. Your ability to follow simple conversations is far too poor to judge others like this. You've admitted that you haven't researched the issue, failed to understand very basic things about what we're talking about in this thread, have clearly not followed any of the references we provided despite demanding evidence (of things that are well known outside this forum!), yet never considered the issue might be on your end even when other people have also pushed back on you.
It's not about ability to follow "simple" conversations. It's about willingness to chase down numerous seemingly-unrelated references (that you didn't even bother providing links for) in order to discover the missing connections that you could have easily explained up front, without much a priori confidence that tracking down those references would satisfactorily fill in all the gaps.
On a forum with such a broad audience, you have to be more careful about assuming which things "everybody knows", and need to put more effort into fleshing out your arguments and explanations. Otherwise, it's hard for people who don't share your expertise or obsessions to tell when you're eliding important information because it can reasonably go without saying in some narrower community you're used to discussing the topic in, or whether you're presenting an argument that genuinely has serious holes in it. The latter happens often enough in discussions where I have expertise that I'm sure it's common when other subjects are involved.
I'm sure we'd both agree that HN has plenty of people who are not qualified to provide expert opinions on subjects like epidemiology. Whatever qualifications you you may have are not on display here, so users such as myself have to estimate your credibility based only on your comments. That evaulation will necessarily be a snap judgement, because there are too many trolls and misinformed people debating controversial subjects, and because someone who is knowledgeable and right but bad at explaining to people not already in the know isn't worth much more of my time and still isn't what people want to find when they come to HN.
If you demand precise scientific rigor in all aspects of everyday life, public health is probably not the career field for you.