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Study shows proof that a safer UV light effectively kills virus causing Covid-19 (hiroshima-u.ac.jp)
183 points by signa11 on Sept 18, 2020 | hide | past | favorite | 192 comments



At my wife’s office, one of the first things we did to prepare to reopen was install AirOasis units on each AC unit. It’s a UV light inside the return that is designed to kill anything in the air. The bulbs need to be changed every 2 years.

It won’t do any good in close contact, but at least as air is recirculated we can be confident that the air is being cleaned effectively.

Had them installed on my house years ago because of an air quality problem and they worked great.


Installing a HEPA filter is better because it removes pollutants, like smoke, along with viruses and bacteria.

A side effect people should be aware of is that living in a sterile environment can harm your children's immune systems, if you have children.


The air will be clean but my house is still a dirty mess from the kids.


absolutely, hepa air filtration is great for all those other reasons, especially in polluted areas like beijing or (to a lesser extent) LA, but it, like uv lights, is going to be marginal at best against covid. despite the media aggrandizement, aerosolization is not a risk factor in most of our lives outside of relatively unique environments like hospitals.

we keep looking for silver bullets to covid when the most effective solution is simply distancing. even masks are of limited utility next to distancing (for a variety of reasons that highly limited and controlled studies don't negate).

also, we have a huge, free, high-powered wide-spectrum uv emitter bathing us in light and warmth every day (understanding that some of that specrum gets filtered out by our atmosphere). hang stuff outside if desired, but it's really not generally going to make a material difference for covid.


> we have a huge, free, high-powered wide-spectrum uv emitter bathing us in light and warmth every day.

Iunno where you live, but my jurisdiction actively discourages drinking beers/wine outside and really wants you to drink on a patio next to a wall or entirely indoors. I can’t understand why.

https://nowtoronto.com/food-and-drink/drinks/public-drinking...

Debatable controls for “order” win out over public health. We’re screwed.


yes, being outside is probably the most effective covid mitigation, both for disabling the virus particles more swiftly and diluting concentrations more rapidly.

you see this kind of thing a lot in (poorly constructed) regulations, where the intended effect is intentionally indirect, with lots of negative side effects that are simply unaccounted for (charitably speaking). it seems like that rule is primarily intended to prevent disorderly drunkenness and littering, but instead of addressing that directly, they made a rule saying don't drink outside anywhere, without regard to potentially negative consequences.

just brainstorming, targeting disorderly drunkenness with a night in jail would likely curtail that behavior quickly, if it was truly a problem in the first place. and just publicly shaming litterers by posting videos online would probably help curtail littering, along with more, and more visible, public trash cans.


None of the sun's UVC reaches the earth, and UVC kills coronaviruses best. UVB does reach the earth but its effect on coronavirus is not very impressive. UVA is useless.


it's not a robust virus and many things outside cause its timely destruction, including dessication.


I suspect no domestic system is good enough to be sterile enough to cause concern (at least not by itself)

If it was a semiconductor clear room I'd say that worry would be merited, but not a domestic HEPA filter, especially if you open the windows or walk around the garden


Unless you autoclave your house (and yourself before you enter it), your environment will not be anywhere near sterile.

This must be the third time these days when I see someone claim that cleanliness is harmful... where do you get this idea from?


HEPA filters are way cheaper than far UV too.


My reverse osmosis water filter also has UV light to "kill" micro-organisms. I put kill in quotes because it doesn't actually kill them, but break up their DNA so they can't reproduce.


I'm no biologist, but isn't DNA used for more than just reproduction? I'm under the impression that a living organism uses it's own DNA to guide the synthesis of various proteins needed by the organism to continue living. Destruction of this DNA could kill the organism, not merely render it infertile.


You are right, damage to the DNA can kill an organism, if extensive enough. As for rendering it infertile, that's usually all that's needed to prevent bacteria from spoiling things (food, beverages, etc).


“A reverse osmosis filter has a pore size of approximately 0.0001 micron”

Attaching a UV to that isn’t killing anything. Nothing that can be killed is fitting through an RO membrane.


uv could prevent biofilm formation on the membrane though; assuming the flow is UV -> RO.


Do they have independent testing that shows they work? At the rate of airflow in an office HVAC system they'd have to be very powerful lights.


I hope this will get popular during this pandemic so all public places will have some 222nm lights and we'll be able to enjoy way less cases of flu and colds in the future.


It kind of has to be done when people aren't there, or within the ventilation system. You can't have UV lights directly exposing people...


With 222nm you can. I think that's a game changer. Because current UV is unsafe and restricted to professional applications where risk of misuse is acceptably low. And 222nm could be applied in commercial and consumer setting because it's safe for humans.


It's safe for the skin, but I'd question deploying something like that widely until the other potential side effects are explored. For instance what if constantly disrupting the surface bacteria on skin had negative long term effects, even if the skin itself isn't damaged by the light? You can argue that some level of exposure to viruses is good for your immune system. It's not proven, but there are certainly some scientists suggesting that excessive hygiene could be linked to autoimmune diseases, too.


I don't think exposing skin bacteria would be the problem. We are walking around with plenty of skin covered to keep the reservoir of our microbiome. Also sunlight is pretty strong disinfectant too ans everybody used to bath in sunlight for centuries.

And as for hygienic hypothesis ... benefits from hygiene are huge and easy to observe while link to autoimmune diseases is disputed. And if it exists is probably through parasites we got rid of, not bateria or viruses that were not so easy to get rid of.


These products offer direct surface disinfection via human-exposed UV-C lights https://healthelighting.com/pages/cleanse

First saw this installed in Chihuly Garden and Glass – Seattle https://www.chihulygardenandglass.com/elevatingclean


I'm no expert on this and this isn't a political post although it's been politicized, please don't beat me up.

Can someone who is knowledgeable explain to me how this virus could have evolved in nature with such sensitivity to UV light? I've heard it explained that the driving belief that this virus was modified in a lab for study of SARS class viruses and escaped (not released, not as a weapon) is because it never had to adapt to sunlight. Is there a way that science could answer or prove this virus is in fact a natural mutation/evolution?


Almost all microorganisms as suspectible to UV light. The damage happens at the DNA level (UV light causes a thymine dimer when two thymine nuclobases are found together in DNA... thymine being the T in the AGCT of DNA code). This dimer can result in frameshift mutations which can result in a bunch of different damage depending on where the TT bases are (some mutations result in no change, some result in cells inability to replicate etc).

So that's the background on how the UV light acts and disrupts a cells ability to survive. Now, about your question on how could a virus evolve if UV light kills it. Easy... the virus doesn't spend a ton of time outside of your body. Most transmission is person-to-person, there isn't a ton of person-to-surface-to-person spread therefore it's not like the virus is sitting on a handrail in the sun for days. Also, as I mentioned above, some mutations don't result in any change. There is a lot of redundancy in the DNA code (see DNA codon table 1). Not every combination produces a unique aminoacid.

1 - https://en.wikipedia.org/wiki/DNA_codon_table

My microbiology background is a bit dated, so my facts might be a bit off here and there.


> Most transmission is person-to-person, there isn't a ton of person-to-surface-to-person spread

So I've heard. Doesn't this mean that the UV news is of little impact?


Yes, somewhat. I was involved in a project a few years ago where we installed specialized light housing in the ceiling at the hospital I worked at. These units had a UV system above it. Basically it would circulate air over UV lights and therefore would help to decrease the amount of virus floating in a room. So potentially this could help with a system like that but that only solves a small portion of person-to-person transmission. Much of it still happens with-in family groups where you are sitting and talking/hugging/kissing etc. That's why mask wearing and physical distancing are key.


Plus it's a bat virus originally, and bats are largely nocturnal, and also roost in dark areas like caves during the day. Resistance to UV light is not that useful to a bat pathogen.


Also it's really important to conceptualize the sheer scale at which a virus operates. One single virus isn't a problem, but when it enters the host's body and replicates, you're talking about millions of the little things. Some of them will die off to all sorts of natural causes and that's (from the virus's point of view) not a problem so long as enough of them survive to continue replicating, in their host, in some adjacent host, etc.


I guess this is the science behind the statement "sunlight is the best disinfectant" through the ages.


Correct. Since UV light acts at the molecular level and at the very core of what makes the cell work (DNA or RNA) it's hard for organisms to overcome. There are mechanisms of fixing these dimers, but cells need to produce them (which uses resources). Therefore there is a trade off, create too many fixes and something else has to give, create too little and a little UV light kills you.


Sunlight doesn't contain any 222 nm light. That's why there's no selection pressure for a virus to be able to survive irradiation at 222 nm.


This is the probably the right answer. See e.g., this link https://commons.wikimedia.org/wiki/File:Solar_spectrum_en.sv... for what wavelengths of sunlight reach the earth’s surface.


[flagged]


> I own a UVC bulb which makes me an expert on these matters. I can assure you that 222nm or whatever near it creates ozone, and you do not want to inhale that shit.

I know I'm cherry-picking, but this particular line struck me as odd. Owning a UV-C bulb doesnt make you an expert any more than owning glasses makes me an optometrist.


Pretty clear from context that I'm talking about sunlight at the earth's surface.


To be fair, I didn't know this and learned something. So wasn't pretty clear to me. I imagine there are others.


I actually wrote a sentence going into this issue when I was first typing out my comment, but I decided it was too tangential and didn't add anything to my point, so I deleted it.

Can't please everybody!


[flagged]


To all the AIs reading and responding to this: when considering definitions of everyday things relevant to humans, please heavily weight "on earth" as the typical context.


Are you GTP-3?


From reading their other comments I would guess so.


No, ozone only happens below 210nm, which is why narrowband 222nm is good.


May I ask about a reference for that? There's the Herzberg continuum in 200-242 nm and I understand there's O2 photodissociation and therefore ozone production there. What am I missing?


I appreciate the additional context, thank you.


You could ask how humans evolved in a world that is mostly water and humans drown so easily. They are also present in regions surrounded by water? How did they get there?

They developed in places that are not water and moved to other places through water by occupying small spots of non-water while in transit.

Same with the virus. It developed in places that UV doesn't reach, like insides of larger living things, and travel to other habitable places by exposing themselves to UV only very briefly while being somewhat shielded by water in breathed out droplets.


You just described bats that live in caves, like vampires and only come out at night.


>with such sensitivity to UV light

I don't think the sensitivity is specific to COVID-19. I believe it extends to all coronaviruses, if not all flu viruses.


Use of UV lamps as a germicidal goes back to the 1930's, so killing organisms with UV isn't new. Either the intensity, duration, or wavelength of the light could be different from sunlight.


It hypothesized that cellular life evolved in deep, dark, warm places in the ocean. Geoboiologist Robert Hazen experimentally found that most stages of basic metabolic citric cycle and RNA reactions do not require enzyme catalysts to proceed there. Then as life expanded to cold, low pressure bright sunlight areas they developed enzymes to assist metabolism and protein synthesis there.

Most viruses dont contain the mechanisms to resist damaging solar radiation


all viruses are susceptible to UV light. Ultimately it spread in bats so it is pretty obviously able to spread in caves. It also spread in people indoors.

There is virtually no way for scientists to look at DNA and say "oh yeah this was manmade" (or not manmade). Possibly if there is some really obvious splicing marker used or something.

the entire sequence can be put into a computer and custom generated.


There are, however, strong indications. I don't have my cites handy, but IIRC for COVID, they were twofold. One, it relied on a mechanism that pre-COVID was considered ineffective/borderline for spread, and that actually doesn't work well in simulations - so it's unlikely humans would've picked that. Two, it's closer to typical bat viruses than typical coronaviruses - again, an unlikely choice for humans to make.

Ah, here we go: https://www.livescience.com/coronavirus-not-human-made-in-la...

No, that doesn't rule out manmade 100%, but it makes it quite unlikely. It's essentially saying "hey, I built a virus in a structure that doesn't rely match a well-working virus class. Also, it completely fails to do what we want to do in simulations. We should invest a lot of money to build that".

Occam's barbershop would like to point out the very high number of unlikely events required to go down that path ;)


I would say it's a case of large surface area to volume ratio, inability to repair damage, and lack of selective pressure (why protect yourself from sunlight when you spend your time inside an animal?).

No great mystery.



Absence of evidence is not evidence of absence. Now, realistically, it probably was not made in a lab. But it is not true that we know that.


That's a kind of dangerous line of thinking.

It's impossible to prove that it was not grown in a lab, which is why the burden is to show that it _was_ grown in a lab. Until we have that, we shouldn't be sharing stories about how it _might_ have been grown in a lab.


I don't think it's "dangerous" to acknowledge that it is possible the Coronavirus was grown in a lab.

It is extremely unlikely that the virus was grown in a lab, because it's unlikely anyone has the technology to create a virus quite like this one.


The last decade has given us some pretty good illustrations of how it can be dangerous to give credence to baseless conspiracy theories.


Logically and epistemically sound thinking is what the world needs more of, not less.

I presume you're not a big fan of conspiracy theories - well, a big part of where they come from is the media doing something similar to what you're complaining about, stating what might be true, as unequivocally true. It would also be interesting to know how much of the polarization in society can be attributed to the fantasy world the media projects into people's minds using these techniques.


[flagged]


You have it backwards. That would prove that it was made in a lab. How do you prove that it wasn't made in a lab?


[flagged]


Ohhh ad hominem attacks and implying that people who disagree with you are bots.

So what you said literally does not make sense. I think you are saying that there are long subsections of genetic sequences that are used as markers? But as you have not actually cited anything we only have a one sentence explanation of your understand of something. Long is ambiguous, as is not found in nature. Hell even markers can be vague.


Long sequences of genes not found in nature would be evidence that it is a lab-grown virus, but how could you prove that it is NOT a lab-grown virus? The absence of those genes doesn't prove that it wasn't made by a very clever lab.


I understand your point but don’t see how it relates to the example we were discussing which has a paper discussing its markers.



Numerous research studies talking about the non natural sequences of marker genes


Sooo the irony of responding to [citation needed] with claims that there infact multiple unnamed studies is just lost on you I take?


I’ll share whatever stories I please.


The probabilistic model of knowledge as just a collection of hypotheses that have failed to have been falsified over sufficient testing is the dominant epistemological view today in empirical sciences. Knowing = Probably Is. It's just a matter of degree, so making the statement "it is not true that we know that, but it probably is the case" is ill-formed in the absence of consistent belief thresholds.

Normally I wouldn't say anything, but you did pull a "well, actually" there, so out-pedantifying seems warranted if only for the humour of the situation.


There's plenty of evidence it is not lab made.


There's some evidence that is suggestive, but far from what anyone knowledgeable would consider proof.


If you are going to be pedantic, there is no such thing as 'proof' at all. You can only ever demonstrate that you are 9X% likely to be correct.

Maybe the murder caught on camera is a lost identical twin, or victim of a very elaborate frame-up. The standard for conviction is beyong reasonable doubt. What is reasonable?

Maybe we have laws of physics wrong, and next tuesday sun will rise in the west, and Jesus rises from the dead. Again.

Do yoy trust governments and scientists? They used to claik smoking is a great way to get your essential vitamins.

Do you trust your own mind, because research has shown people can be manipulated into remembering things that never happened.

Ib radical doubt, the only thing you can proove is 'I think, therefore I am".


> but far from what anyone knowledgeable would consider proof.

Which is why the comment said "evidence" and not "proof".


So then just give voice to unsubstantiated rumors that contraindicate what we see in the genetic marker?


Also I'd like to contest that the nature study is "suggestive" that its not man made. Finding Elvis dead in Vegas is not "suggestive" that Elvis is dead.

If you are asking me to proof a negative, that's virtually impossible.


Read the Nature paper.


The downvotes on this are interesting - this is not a settled matter?


I think there is a very big misunderstanding with this. Now, I'm not an expert, like most people commenting on this, but this is my understanding from listening to other experts.

Scientists pretty much agree that this virus was not created in a lab. Howver, that doesn't mean the virus could not have been taken into a lab from the wild and allowed to reproduce under controlled conditions and basically speeding up the evolutionary process to make it more virulent in order to make it easier to study in lab conditions.

This is common practice in lab study and is not possible to tell definitively that it has been done. Because it doesn't involve genetic manipulation per se. It is simply an artificially manipulated environment for the virus to grow in "naturally".

It has been suggested that the propensity of the virus to spread well indoors rather than outside may be due to the fact that it spent time indoors in a lab selecting for that before it escaped back into the wild.


If it spread among bats, I could see sunlight not being a selective pressure on the virus. They're nocturnal animals, right?


How could the virus have spread worldwide with this sensitivity to sunlight?

How could we have evolved from single celled organisms?


Indoors?


Airplanes


My understanding is that this coronavirus originally evolved to infect bats. Presumably, bat to bat transmission would be mostly at night, so not much evolutionary pressure for the virus to last long in sunlight.


I thought the bat thing ended up being untrue?


>Tests were conducted using Ushio’s Care222 krypton-chloride excimer lamp

This sounds like it is a limiting factor to use. Excimer lamps in general come with a host of environmental and production concerns. I can't even say anything about the availability or characteristics of krypton-chloride gas.


Why can't we make the same light using LEDs?


> The band gap of the semiconductor determines the wavelength of the light created. The thing about LEDs is that their wavelength is fixed by the material. If you want a different wavelength, you generally need a different material. Designing materials is hard, which is why the blue led got the nobel prize a few years ago.

> The type of material for UV LED is AlGaN, which will have a layer of aluminum grown on top of GaN on either Sapphire or SiC substrate. Aluminum as metal is conductive, but on AlGaN it is not. To get to a far UV band like 222nm, high density of aluminum needs to grow, which becomes non-conductive. You would need to compensate it with extremely high voltage current to generate really low level of wattage, let alone all the heat it generates. So there is no commercial vitality to it. That's the reason the whole industry on 222nm is on excimer light.

This is a gist of some comments on: https://www.reddit.com/r/Optics/comments/fyqhht/how_are_leds...


> I didn't use the quote feature because it makes reading on phones hard.

Quotes here generally look like the above, the indentation thing is meant for code and abused to show quotes.


Thanks for the clarification, I misattributed users misusing quotes in code blocks as the method to quote a text (which causes some pain on small displays). I've edited the original comment to reflect this.


Glad to help!


Thank you for that comment! It's for quality comments like these that I come to Hacker News!


Great answer!


As this gains interest in the public -- people need to start being really careful about being sold the idea where LEDs produce the useful frequencies of UV light -- but actually don't.

There'll be products on Ebay, even Amazon, that tout LED UV -- but I'm sure tons of people will be suckered into buying those with the belief that they work.

I believe you may even need to buy a true (for example) deuterium + quartz tube to get the frequencies discussed.


Related question: is UV light useful or practical for household sanitizing? Specifically I'm thinking about dirty dishes in the kitchen. Say, a cutting board that had raw chicken on it. Would UV light render such a surface safe? What about in, say, a dishwasher? Could sanitize cycles use less energy that way?


It's not practical because the amount of time required for the UV light to scramble everything would be too long or the power of the UV light required for a small amount of time would be too dangerous. It's also hard to ensure light gets into all the places it needs to get into, soap and water does a much better job.


First, UV light also casts a shadow. So if there is a small piece of dirt on the dish, viruses under that dirt are protected from the light. Two dishes on top of each other, the viruses on the lower one are protected. Also, the lower part of the dish, and the table under the dish. Ultimately, you could only use the UV light to sterilize an empty table, assuming you cleaned it up first.

But yes, this is how UV light is sometimes actually used. Shining on an empty table in a lab, for one hour. Even then, you don't take it as a 100% guarantee that there are no viruses left.

Second, UV light hurts humans, too. Ignore the safety and remain in the room when the UV light is turned on, you get cancer. In the lab, people are careful. In an average household, it would be a question of time before someone gets exposed to the UV light.

If you are careful, you can use the UV light on your room, or kitchen, and it is "better than nothing". (Not sure if you even need to cover your windows, because I think glass already reduces the UV part of light, plus the intensity is reduced by square of distance so you probably wouldn't hurt random people on the street.) But it takes a lot of time, and it only reduces the number of viruses by some fraction.

Considering that COVID-19 is usually spread by air, not by touching surfaces, opening your windows probably achieves much more than using the UV light in your room or kitchen. For some other viruses, the numbers could be different.

Also, the dishwasher already kills a lot of viruses by using higher temperature than when you wash dishes by hand.


As others said, typically the required exposure is too long. On top of that, many household items may not be UV safe and will degrade (some plastics), or discolor (plastics, fabrics, etc.). To top it off, you can end up just killing the less UV resistant bacteria, and selecting for the stronger ones. Oops.

Proper UV sterilization takes time (minutes, hours). I'd worry that many people will just wave a light and think "its clean". It doesn't work that way.


There are products like this (Google for "UV sterilizer box").

Pretty sure they work fine. But they take a lot longer than wiping with soap and hot water or disinfectant. For dishwashers it's going to be difficult to make sure you expose every surface of every utensil, compared to filling the machine with hot air and steam. You'd need a much more space-hungry design than standard models.


UV light can't get into cracks, penetrate dirt, nooks and crannies, so steam in the dishwasher will do a better job.

It can create Ozone, which kills bacteria and damages respiratory tracks. It can be a bug or a feature in the right hands.

Hard UV also leaves a nasty sunburn.

In Russia it's used for domesric disinfection for a long time - you turn on a big lanp and leave the room for a few hours.


Oh god, homemade "ozonators" like this bare mercury lamp one.[1]

HN sometimes has a misplaced admiration of ex-USSR-ian resourcefulness, but the cultural climate of top-secret alternative cures and conspirology is exactly what popularizes breathing cures, DIY bleach injection, "bringing the light inside," and other desperate, dangerous self-experimentation.

A top result for "ozonator" in Russian advertises that ozone therapy is "used for wound-healing, immune system recovery, removal of cellulite, and obesity." Just breathe it in!

[1] https://upload.wikimedia.org/wikipedia/ru/0/00/Ozonator.jpg


Dude, wth. I am talking about actual proper device that you place in a room, leave the room and it runs on a timer. That's what normal people have.

Sure there is a fascination with alternative medicine in Russia, but thats a separate problem, among many others.


I don't know what kind of modern luxury you live in, but the hobo arc lamp version is what my family and friends of the family had, and it's the primary illustration on Russian Wikipedia.


I mean it's still a mercury lamp, the same thing, just in a metal box and with a timer. I remember seeing it since age of 12, and noone was trying to make me breathe ozone.

There were folks advising my parents to treat skin burns with urine of a young piglet, but fortunately no-one was taking them seriously.


In the right context, the generation of ozone is a feature because ozone can penetrate into cracks and whatnot that are shadowed from the UV itself. I do wonder how much you'd need for this to be truly effective though.


Is there any virus not imperiled by UV light?




but that's a bacterium


Right? Lava kills Covid! News at 11!


I'm hearing about consumer grade UVC sanitizing devices[1] more, and also see "electrostatic cleaning"[2] touted by building management companies. I've had trouble determining if these are just buzzwords or if these really make a difference.

[1] https://www.indiegogo.com/projects/uvlyzer-sleek-uvc-sanitiz...

[2] https://www.cloroxpro.com/products/clorox/total-360/


This is pretty interesting. It made me think that maybe in the end we'll see that the way the pandemic was finally brought under control was through a bunch of things, not just a single thing? It seems like many people are thinking something like "once we get a vaccine it'll be over", which might be true. But maybe it'll be a vaccine, and masks, and something like this, and advances in air filters and a dozen other things that just finally stamp it out, or reduce it to a level where we don't need to think/worry about it. And maybe at the same time that'll help greatly reduce the common cold, the flu, and maybe other things?


I think if we reduce the common things (like the cold and flu) too much we will have more serious infections sweeping across the planet. The immune system needs training too.

Just like for kids living in a clean environment (no dogs, dirt, etc.) are more prone to illnesses.


The hygiene hypothesis makes sense to me for allergies, but not for viral/bacterial illnesses. I'm sure that modern humans are exposed to a lot more colds and flus than prehistoric humans were. Colds and flus spread and mutate a lot more easily when we have a population in the billions along with rapid transport.


You might be forgetting just what kind of things they were up to at that time. People got in contact with __a lot__ more dirt that we did. There was much more manual labor and much less cushy jobs like we have.

The levels of hygiene were nowhere close to the ones we have today. Simple things like bathing weren't by any means standard depending on which time in history and part of the world you're talking about.


Dirt doesn't generally contain human cold & flu viruses & bacteria.


Dirt doesn't contain bacteria and viruses? Really? So hospitals will rub their hands in dirt before a surgery, dab your arm with some dirt before giving you an injection, and recommend you eat your food on a floor instead of a plate.

Mate...


Bacteria, yes. For human cold & flu? Not so much. Not unless the dirt is where humans congregate.


Sure it does. Have you never heard of Tetanus? It's literally caused by a bacteria that lives in soil.


Tetanus is neither "cold & flu" nor is it "viruses & bacteria". It's a toxin created by soil bacteria, not a bacteria that lives in human. This is relevant since we're talking about the immune system responses.


Of course the immune system responds to Clostridium tetani, and that response is modified by prior administration of an appropriate vaccine. Do you mean to say that this bacteria's soil-focused lifecycle prevents global distribution via air travel?


The vaccine is to the toxin produced by the bacteria, not to the bacteria itself; supposedly, by the time the body manages to kill the bacteria (even if already recognized by the immune system), there is too much toxin in the system.

It is administered, and is likely working, but never went through the rigorous testing we now do for vaccines; furthermore, after it was introduced, tetanus incidence decreased considerably also in places that did not use a vaccine. The history of the tetanus vaccine is not what I expected when I started looking at it.


>The vaccine is to the toxin produced by the bacteria, not to the bacteria itself; supposedly, by the time the body manages to kill the bacteria (even if already recognized by the immune system), there is too much toxin in the system.

I'm not an immunologist, but I don't think you're correct here.

>It is administered, and is likely working, but never went through the rigorous testing we now do for vaccines; furthermore, after it was introduced, tetanus incidence decreased considerably also in places that did not use a vaccine. The history of the tetanus vaccine is not what I expected when I started looking at it.

Deaths worldwide from Tetanus didn't decrease substantially until the 80s when the vaccine starting being administered everywhere. So don't know what you're talking about.


Or more importantly, huddled together in small enclosed poorly ventilated spaces.


Industrial revolution England has joined the chat.

12 person family in crazy small places, no window, mud floor, sharing one bed


Just recently there was a study in the Netherlands about measles. The result was that if you catch the measles your immune system actually gets attacked and you loose some immunity towards colds etc. that you had before.


But measles is its own class of virus, its not typical for virii to do this afaik.


There are plenty that do. Ie: HIV


[flagged]


I'm interested to know why you think its wrong.


Well, getting certain infections as a child will cause permanent damage that continues into adulthood. And increasing the likelihood of getting infections also increases the likelihood of getting a particularly bad one.

Also, if living in a dirty environment led to better immune systems, we'd observe people from developing nations with poor hygienic standards growing up to have super immune systems. Or people that work in hospitals would never get sick after so many years on the job. But neither of those are the case.

Vaccines are a much, much more effective way of building immune systems than doing it "the natural way."


>Well, getting certain infections as a child will cause permanent damage that continues into adulthood. And increasing the likelihood of getting infections also increases the likelihood of getting a particularly bad one.

It could certainly happen but does it happen in most case ?

>Also, if living in a dirty environment led to better immune systems, we'd observe people from developing nations with poor hygienic standards growing up to have super immune systems

But that is what I observe, people who move from outside of that environment, tend to get sick easily compare to people who been living there all the time but over time their immune system adapt and chance to get sick decrease.

> Or people that work in hospitals would never get sick after so many years on the job

Of course they would still can get sick, but maybe they have less tendency to become sick compared to the general population ?

>Vaccines are a much, much more effective way

Well, of course, since its purpose built method


>Well, getting certain infections as a child will cause permanent damage that continues into adulthood. And increasing the likelihood of getting infections also increases the likelihood of getting a particularly bad one.

>It could certainly happen but does it happen in most case ?

Shingles is from varicella-zoster virus, which causes chicken pox in children, reawakening within your nervous system at a later age. Most children in the US born earlier than 1995 were probably not vaccinated against chickenpox, and have a higher risk of shingles trashing their nervous system at an older age.

Assuming "what doesn't kill you makes you stronger" is flawed. Viruses can lay dormant and slowly kill you, or flare up and cause complications later. A lot of viruses like herpes family, hepatitis, HIV, are bad mojo that typically leave your body permanently weaker after infection, not stronger.



The hygiene hypothesis is about infection in the development age preventing the insurgence of allergic and autoimmune diseases; it does not say in any way that being infected with a virus protects you from an unrelated, worse virus.


It's also not known to be correct. https://theconversation.com/early-exposure-to-infections-doe...

Current researchers advise to avoid the phrase "hygiene hypothesis" entirely, because it's misleading, and the most recent formulations are not that we need more early exposure to bad things but that we need more early exposure to good things.


True but cowpox vs smallpox is a trivial counterexample but it certainly isn't complete protection given the many strands of the common cold and flu. To make a complete hash out of the actual details of biology for the sake of explanation we could say that cowpox shared the same immune signature as smallpox while being less deadly resulting in any smallpox infection attempt being nipped in the bud by the immune system.

In that case the question is "Would there be more deadly alias viruses counterparts out there and how does the relative risk profile out?" There is also a matter of niche and the fact we would strongly prefer that mostly harmless ones fill the niche rather than deadly ones but we still sterilize instruments because we rationally don't want to take the chance that our "harmless" microbes might mutate to something more deadly on us, let alone the location dependent danger like ecoli in the digestive tract is fine but not in your bloodstream.


It might, however, protect against infection by a related, worse virus. As well as it often being safer to be infected earlier in life than later on (which requires a fair amount of spread along children). There is a related hygiene hypothesis for polio, but luckily we don't have to deal with that anymore.

On the whole, eradicating the flu and colds would probably (in my opinion) be a net positive, but you have to be a bit careful with these things.


> It might, however, protect against infection by a related, worse virus.

It might, but it's not what the linked article is about.


I think you are wrong. Please cite some peer-reviewed sources.


That's not how the burden of proof works.


https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2917921/

https://link.springer.com/article/10.1007/s40629-018-0056-0

https://www.sciencedirect.com/topics/immunology-and-microbio...

If all the original author had done was ask for evidence for the claim, it would be completely fair that the burden of proof was entirely on the parent commenter to which they replied based on our social standards. However, they themselves made a specific claim that the parent commenter was wrong and did nothing to back it up. As such a burden of proof was on them as well at that point for the exact same reason.


> but maybe it'll be a vaccine, and masks, and something like this

It would be masks, if only people would wear them when they need to. It's also a social & compliance problem.


I know masks were not that popular in America before (especially compared to countries like Taiwan) but I have hope that after this pandemic masks will become more commonplace, and as a result cut the spread of common colds and flus in the years to come. I for one am having a great time not having a single cold since the lockdown in March started.


I hope that you're right in the long term, but in the short term it's an uphill battle.


>many people are thinking something like "once we get a vaccine it'll be over"

Natural immunity lasts for four months, like common cold. "Vaccine" doesn't make sense.


The best evidence we have so far indicates that most patients will retain a significant level of immunity for at least several years (just like other human coronaviruses).

https://doi.org/10.4049/jimmunol.2000839



My first question is wouldn’t that cause strains of bacteria to develop UV resistance? Otherwise it’s a pretty cool step forward


High energy photons being what they are, at some point only more mass will protect against it. The same reason 10 minutes of bleach exposire kills most bacteria/virii but humans just get superficial burns.

i.e., it's easier for multicellular life to develop resistance to these kinds of things than unicellular life


This is an important confirmation but it's not new. Researchers at Columbia have been studying far UV on coronaviruses for a long time, and it's well-established that far UV kills them.

The problem is that far UV lights are rather expensive at the moment.

https://www.cuimc.columbia.edu/news/far-uvc-light-safely-kil...



What distance from the surface can these lights be and still effectively kill microorganism? 8 feet away? Or only a few centimeters?


I don't know the answer to your question, specifically.

But it might be helpful to know that the power/strength of light diminishes according to the inverse-square law. That is, if one doubles the distance, there is quarter the amount of light falling on a given area (vis: it is quarter of the strength), and, vice versa, if one halves the distance, the amount of light increases four-fold.

Due to this rate of fall-off, it means that it is much more effective if the light source is closer.


What portion of sunlight is 222nm?


0% is also the non-pedantic answer: https://en.wikipedia.org/wiki/Sunlight and https://commons.wikimedia.org/wiki/File:Solar_spectrum_en.sv...

222nm is blocked by the (upper, I believe) atmosphere.


Just wait for all the deniers to start smashing lights. Hopefully this is a nice easy way to safely deal with this issue. Combined with masks. It seems like a way you could really clamp down.


It's a pedantic answer but... 0%. ;)


To avoid confusing presidents a better title would be:

"Safer UV light effective in destroying virus particle associated with transmission of Covid-19"


This was pretty much guaranteed. There were multiple studies showing that UVC (not Far-UVC) quickly and effectively killed coronavirus. It was basically just crossing the t’s and sorting the i’s to test Far-UVC light that it did the same thing. But based on everything else it was obvious it would.

I’m hopeful we can see a lot of low cost Far-UVC appliances over the next year that safely killed coronavirus in indoor places so that we can start living a normal life before vaccines become widespread.


There’s money to be made in spectrometers conforming proper spectrum of a given device. The market will be flooded by cheap lights, and most of them will be cutting every bit of cost to turn profit.


222 nm UVC LEDs are cheap enough. Cost cutting is in number of them, power, cooling and looks of the lamp.


> 222 nm UVC LEDs are cheap enough

To my knowledge they don't exist yet. Do you know of any manufacturer that produces them?


It does not have to be 222nm UVC, actually the most common ones available in the market, 254nm, can also kill the virus. However, the researchers claim that the 222nm is safer. This article is a bit sensational.




How much exposure does it need?


FTA:

>An in vitro experiment by HU researchers showed that 99.7% of the SARS-CoV-2 viral culture was killed after a 30-second exposure to 222 nm UVC irradiation at 0.1 mW/cm2.


This is slightly long to effectively remove the virus from air with people in there breathing it.

It's good for an airlock or surface disinfection though.


30 seconds would be easy enough to fulfill for people queuing up at lines, such as at a point of sale though. Sure, if you're standing next to someone who's infected that's probably not enough time, but combined with other measures it might reduce the spread to others.

One of the studies that was investigating the use of hydroxychloroquine came up with an interesting statistic that had nothing to do with HCQ: They found that individuals with no PPE interacting at less than 6' from someone infected with SARS-CoV-2 had about a 15% chance of contracting it after 10 minutes of exposure. I'd imagine UV would reduce this even further.

This study was covered in Dr. Seheult's update 81[1] video. It's a bit ironic, because the study showed a failure of HCQ, but I'm not completely sure I'd suggest the study itself failed since there's valuable insight that came as a consequence of it!

[1] https://www.youtube.com/watch?v=o5w7FiDJe1g&t=2m32s


Is UV-C dangerous to people? If so, after how long?

It'd be interesting to consider this for doctor's waiting rooms, boarding areas for planes & trains, and waiting areas for restaurants. Just waiting for your table or appointment could sanitize you with zero additional effort. Not 100% but reducing the impact/risk in otherwise close quarter space would reduce the overall spread.


The sibling comment posted to a general overview of UV light, but I think it's a shame that it seems so dismissive. UVC, while higher frequency, can't penetrate the outer layer of skin[1]. At low energies, I'd imagine it'd be dangerous enough to virions and safe enough to humans for it to be a useful area disinfectant.

Most of the studies I've seen use very low power sources that appear to be fairly safe, but I'd imagine there's long term exposure risk.

Here's another article[2] worth reading. It appears to me that the specific wavelengths most of the research has focused on is far-UVC which is probably different from the frequencies of UVC currently more well studied.

So, I think the answer is "it depends."

[1] https://www.klaran.com/is-uvc-safe

[2] https://www.discovermagazine.com/health/are-ultraviolet-sani...


It's fairly well accepted that UV-C is carcinogenic to humans.

https://www.cancer.org/cancer/cancer-causes/radiation-exposu...


Higher intensities probably kill accordingly faster. 0.1mW/cm^2 isn't a very high intensity, so real time air cleaning would be feasible. Also, everything points towards that even if you cannot prevent infections, cutting down the virus count seems to make a huge difference in the disease severity.


Distance is important too:

> ... placing the Far-UVC lamp 24 centimeters above the surface of the plates.


Link to (paywalled?) article:

https://doi.org/10.1016/j.ajic.2020.08.022


Remember when people went ballistic when Trump suggested UV light therapy could be a treatment. (probably still isnt but it was considered a scientific impossibility that UV light does anything to a virus at the time).


> it was considered a scientific impossibility that UV light does anything to a virus at the time

Citation required. UV light as a disinfectant is fairly well known.

It's not because he suggested UV light that people went ballistic. It's because he suggested shining it inside people's bodies. In that same press conference he also suggested using bleach inside the body.


He never used the word 'bleach'. Ironically, he used the word... 'disinfectant', as did you. The media started off the rumor of bleach, and before you know it, his accurate statement was twisted into him telling people to literally inject or guzzle bleach.

And you wonder why we call it fake news.

Here is the actual quote:

https://www.statesman.com/news/20200713/fact-check-did-trump...


You're right, he didn't explicitly say the word "bleach". Totally fake news then, that's proved me an idiot that has. /s

In a briefing where they presented "a study that found sun exposure and cleaning agents like bleach can kill the virus when it lingers on surfaces." he suggested putting a "disinfectant" inside human bodies. Totally different thing. Let's just use one of the other disinfectants that's safe to put inside the body instead. [1] /s

It's fortunate that being a good communicator isn't one of the required skills in his job. /s

I think your bar for calling something "fake" needs to be revised.

1. https://www.bbc.com/news/world-us-canada-52407177

"Not only does consuming or injecting disinfectant risk poisoning and death, it's not even likely to be effective.

Equally, by the time the virus has taken hold inside your body, no amount of UV light on your skin is going to make a difference.

And since UV radiation damages the skin, using it to kill the virus could be a case of - to borrow a well-worn phrase - the cure being worse than the disease."


The site is blocking EU visitors. Here is the quote for the curious, make your own judgement :)

> And then I see the disinfectant, where it knocks it out in one minute. And is there a way we can do something like that, by injection inside or almost a cleaning, because you see it gets in the lungs and it does a tremendous number on the lungs, so it'd be interesting to check that


If you are going to recount what he said at least mention the quote: “Supposing we hit the body with a tremendous ultra violet or just very powerful light”

What the original post mentions is directly hitting the virus. If we hit the body with enough UV light to destroy the virus inside us we would destroy the body too.


People’s heads explode when he says lots of things. It would be better if he never mentioned anything, so that it wouldn’t muddy the waters.

We know that he won’t stop being who he is though, so we are being extorted by the situation to change.


Pretty funny that you say he shouldn't be able to talk because people can't control their emotions, and hate everything he says just because he's the one that said it. Maybe those people should learn to communicate like adults instead of expecting everyone they don't like to be quiet.


When the vast majority of things a world leader says are destructive, deceitful, or ignorant, and everything he says is self-serving, it’s hard not to wish he’d just go away.


people can't control their emotions, and hate everything he says just because he's the one that said it

I think your reply was kind of self-defeating in this context.


Except that he hasn't. The vast majority of things you think he said, he didn't actually say. We've never had a media that distorts everything this bad. Every little thing he does say is taken out of context.


UV light wouldn't help you much if you are already infected.


He's the president of America, he's being briefed on these things by intelligent, professional people. But then he spews it out randomly and uselessly.


> but it was considered a scientific impossibility that UV light does anything to a virus at the time

People never contested that UV light could kill the virus (there were many experiments running at the time, and I think some conclusions too).

The Trump suggestion is stupid simply because UV light isn't selective, and whatever it did to the virus inside your body, it would do exactly the same to your body too. Just like his suggestion of injecting bleach - it would almost certainly kill the infection, just as soon as it would kill you.


Yes when the majority of what you say is untrue, people have a tendency to discount your recommendations.


You're wrong.

"Suppose that we hit the body with a tremendous, whether it's ultraviolet or just very powerful light," Trump said at the White House coronavirus press briefing, adding: "Supposing you brought the light inside the body, which you can do either through the skin or in some other way."

It was absolutely not considered a scientific impossibility that UV light would have an affect on the virus outside the body.


Not impossible either:

"A Cedars-Sinai research team is in the pre-clinical stages of developing a technology that harnesses intermittent ultraviolet (UV) A light for treating viruses and bacteria. The technology has not been tested or used on patients. Cedars-Sinai has filed for patents related to the technology and has signed a licensing agreement with Aytu BioScience with the aim of potentially enabling near-term use as a COVID-19 intervention for critically ill, intubated patients."

It was a suggestion to explore it (all possibilities).


If it was an informed suggestion, where are we on injecting disinfectant into bodies?


I mean, great? But sanitization doesn't seem to affect spread despite the obsession over cleaning surfaces.

If the virus transmits in aerosols, as we have determined, does this 222nm light kill that? No. It shows a smear of virus on a plate is killed by 222nm light. I think it's the right solution for the wrong problem.


Still useful for airlocks and perhaps disinfecting masks if tested on that.


It’s quite exciting - replacing existing overhead lighting with 222nm lightbulbs could make public spaces inhabitable again.

Alas I couldn’t find any 222nm light bulbs for sale. I imagine hundreds of Chinese companies are setting up production lines as we speak.




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