Tl;dr Putting copper tape on commonly-touched surfaces is a high-value thing to do in the case you’re actively trying to avoid infection, since copper kills viruses and ~~50% of viral disease is from hand-to-surface-to-face contact (h/t Adam Scholl for hypothesis) [ETA: coronavirus seems to have mostly (?) respiratory droplet transmission, so this prior is less relevant but still worth intervening upon]
Amazon link (sadly, probably one Amazon item that won’t go out of stock)
Metals killing bacteria is well-documented, like all the very consistent results in this paper comparing 9 metals (lead kills slightly better than copper but that unfortunately extends to the humans; zinc and some other metals also kill pretty well, only two did not). Within an hour, copper dropped CFU from 10^6->10^1 (the measurement threshold). Zinc took 2 hours, nickel 4.
Unfortunately, this isn’t in widespread use in hospitals yet. But when it does, copper on the most-touched surfaces of an ICU appears to reduce infections by about half (bed handles, chair armrests, nurse call buttons, and a few others). But these are in very high-germ-load environments. What happens in a normal home?
First, how much of disease spread is from hand-to-surface vs airborne or hand-to-hand? I lost the citation and it wasn’t well backed, but apparently you don’t catch colds through suspended particles very often (someone has to sneeze within 6 feet or exhale in your face lots). And hand-to-hand contact spreads it more efficiently but (one paper said) less frequently than hand-to-surface-to-hand, especially in environments without lots of high-fiving and hand-shakes. Plus, the study saying 50% infection reduction from copperizing main surfaces would fit well with a base rate of ~70% hand-to-surface infections and, of these, ~70% of touches in the ICU got sanitized by the dangerous surface metal coverings. But 70% sounds like a lot so I’m going to be a little conservative and just say 50%.
Now, it’s hard to figure out how many things you’d need to cover with copper to reduce most of this. But some typical commonly-touched shared items are:
doorknobs (brass is probably ok, steel is not) [ETA: comment below points out brass not ok]
light switches
faucets
toilet handles
refrigerator
drawer handles
writing implements
backs of chairs
Depending on how many people you are sharing touch-space and not air-space with, I expect covering these in copper could reduce infection by anything from 1 to 50%, though I expect in a typical house of four people who sometimes venture outside and don’t know about never touching your face, you’d get an effect roughly between 15 and 40%.
This study describes “detecting viable virus” as having a threshold of 10^0.5 TCID50/mL, and they assume exponential decay of viable virus particles.
I’m really confused by their numbers, tho; it looks like cardboard has a hundred-fold reduction in 23 hours, from 10^2.5 to their detection threshold of 10^0.5, which I can’t square with the 8.5 hour half-life. [Edit: it looks like I’m potentially confused about what TCID50/mL means?]
I also don’t know how to compare their detection threshold with the point at which I should be willing to handle a cardboard box (with varying levels of cleaning and PPE). Is their test basically as sensitive as my immune system (in that I shouldn’t handle something where they could see a viable virus, and can handle something where they can’t)? Or should I be letting boxes sit for 3 days?
I had the same confusion over the half life ratings.
TCID50/mL is how much you can dilute a sample and still have it kill half of the cells in a sample. This suggests that the natural reading of those graphs is correct.
I estimated some numbers off the graph and it looks like what they are calling half-life is actually 1/5th life, so either we’re both missing something important or there is an error somewhere.
Worth noting that a lot of metal handles will be coated with a finish that prevents you from actually touching the metal. This is because these metals (especially copper) can leave a strong metallic smell on your hands which people typically dislike, and also because it prevents the metals from tarnishing. These handles will not help reduce infection and will need copper tape on them.
Sorry, forgot to modify this for a virus-specific claim, but yes.
On solid copper, H1N1 decreased by 4 logs in 6 hours in this review; vaccinia and monkeypox viruses were reduced by 6 logs in 3 minutes in this study; murine norovirus was destroyed in 30 minutes in this study, though it doesn’t work very well at 4C; and another review says that copper oxide filters neutralize all of “bacteriophages [58-62], Infectious Bronchitis Virus [63], Poliovirus [61,64], Junin Virus [59], Herpes Simplex Virus [58,59], Human Immunodeficiency Virus Type 1 (HIV-1) [11,65-67], West Nile Virus [11], Coxsackie Virus Types B2 & B4, Echovirus 4 and Simian Rotavirus SA11 [68]. More recently, the inactivation of Influenza A [55,65], Rhinovirus 2, Yellow Fever, Measles, Respiratory Syncytial Virus, Parainfluenza 3, Punta Toro, Pichinde, Adenovirus Type 1, Cytomegalovirus, and Vaccinia [65]”.
Wikipedia suggests copper can kill at least influenza A virus and adenovirus. It seems likely that it would be effective against other viruses too, though not clear (to me) if it would work against every virus.
This ERI review concludes that there was really only one RCT (the one you linked), and they found that the study didn’t actually reach significance
Our calculation found that the difference in the HAI rate (regardless of MRSA/VRE colonization status) between the study groups was not significant (copper-equipped ICUs: 17⁄294 [5.8%] versu snon-copper-equipped ICUs: 29⁄320 [9.1%]; p=0.123). The median length of stay for both groups was four days (p=0.74). The reported mortality rate was 42⁄294 patients (14.29%) in copper-equipped ICUs versus 50⁄320 (15.63%) in non-copper-equipped ICUs(p=0.64).
What’s going on here is that Salgado splits outcomes into 4 groups, nothing, infection, colonization, and both, and finds a difference between the 4 groups. The review says “I only care about infection” and compares infection vs non-infection, and finds no significance. Each version of their math checks out, but I’m inclined to trust the review here.
If it’s a cheap countermeasure that aims, in the better estimate, for a 50% reduction of a small risk I think you’d be better off asking yourself if you’d buy it at double price rather than deciding which of the equally persuasive, conflicting experimental evidences about its efficacy you should trust. Also if you’re worried about non monetary costs like hand skin damage, I guess you’d better decide if you’d put up with the same cost for a 25% risk reduction.
Earlier I heard something like “wrinkles in the copper can reduce the effect, something something the fluids get caught in little pockets and leave spots that don’t touch the copper.”
Have you heard anything about that and have any thoughts on that? A lot of the images I see of people coppering their doorknobs are particularly wrinkly, and I’m wondering how much effort to put into getting everything smooth.
Not that it’s necessary to make this comment complete, but I’d love to hear more about that 50% estimate. I’ve had a very hard time getting data on that.
Is there a reason we’re not spamming reddit/discords etc. with this advice?
I don’t have enough karma on reddit to do things, but r/china_flu, r/lifeprotips, r/todayilearned all seem like good places to post this information.
Additionally, it might be worth it to spam amazon listings of copper tape with reviews saying it has antiviral properties. Possibly contacting the sellers of the tape as well.
Because ‘spamming’ is a rude way to force people to pay attention to you, and should be discouraged. But posting the information in ways that follow community norms seems good, although I’d want to think a bit about prioritising messages to spread—quite plausible to me that advertising the need for expanded capability to supply oxygen to people is more important.
The time of contact killing listed among the different microbes ranges from 1 minute to over a week. I don’t know which example of a microbe would be closest to copper.
One big problem that may exist with using copper that I came across is that copper may reduce in efficacy if it is frequently cleaned, whereas stainless steel is fine to repeatedly clean. Source
The cleaner suggested to be used on copper surfaces without reducing its efficacy by this paper .
That seems useful. You forgot one of the most commonly touched items—phones and computers. I am gonna put tape on the back of my phone case and my laptop.
This is a good point, but for what it’s worth I don’t fully endorse coppering your phone (mine isn’t coppered). Several people have anecdotally reported it being uncomfortable or irritating on their hands, or receiving tiny cuts from the copper, etc.
Absorption through skin is incredibly low, but I do take the risk of open (if tiny) hand wounds seriously, and also generally try to reduce my total copper contact in case anything weird does happen, since this is not tested by time.
You touch these often, yes, but how often do you share them with other people? If all the germs on there are yours, maybe disinfecting it is not really helping.
But if you are constantly handling your phone it will reduce the value of frequent washing/sanitizing of hands, since anything you do get on your hands will transfer to your phone.
Although, I don’t know what the numbers look like for transferring virus when a touch occurs—e.g. if we look at a path like “handshake → touch phone → [wash hands] → touch phone → touch face”, how much of the virus is left after four sequential touch events like that? Perhaps this kind of secondary contamination is not actually a huge deal? I have no idea.
A powder called Glo Germ, meant to visualize germ spread, was still visible to the naked eye after 8 handshakes (but not 9) in an informal experiment by YouTuber Mark Rober. ( https://youtu.be/I5-dI74zxPg?t=346 )
This is my usual attitude, but given the evidence that coronavirus is very long lived on surfaces and reinfection is possible, it seems worth it to me in this specific case.
Tl;dr Putting copper tape on commonly-touched surfaces is a high-value thing to do in the case you’re actively trying to avoid infection, since copper kills viruses and ~~50% of viral disease is from hand-to-surface-to-face contact (h/t Adam Scholl for hypothesis) [ETA: coronavirus seems to have mostly (?) respiratory droplet transmission, so this prior is less relevant but still worth intervening upon]
Amazon link (sadly, probably one Amazon item that won’t go out of stock)
Metals killing bacteria is well-documented, like all the very consistent results in this paper comparing 9 metals (lead kills slightly better than copper but that unfortunately extends to the humans; zinc and some other metals also kill pretty well, only two did not). Within an hour, copper dropped CFU from 10^6->10^1 (the measurement threshold). Zinc took 2 hours, nickel 4.
Unfortunately, this isn’t in widespread use in hospitals yet. But when it does, copper on the most-touched surfaces of an ICU appears to reduce infections by about half (bed handles, chair armrests, nurse call buttons, and a few others). But these are in very high-germ-load environments. What happens in a normal home?
First, how much of disease spread is from hand-to-surface vs airborne or hand-to-hand? I lost the citation and it wasn’t well backed, but apparently you don’t catch colds through suspended particles very often (someone has to sneeze within 6 feet or exhale in your face lots). And hand-to-hand contact spreads it more efficiently but (one paper said) less frequently than hand-to-surface-to-hand, especially in environments without lots of high-fiving and hand-shakes. Plus, the study saying 50% infection reduction from copperizing main surfaces would fit well with a base rate of ~70% hand-to-surface infections and, of these, ~70% of touches in the ICU got sanitized by the dangerous surface metal coverings. But 70% sounds like a lot so I’m going to be a little conservative and just say 50%.
Now, it’s hard to figure out how many things you’d need to cover with copper to reduce most of this. But some typical commonly-touched shared items are:
doorknobs (brass is probably ok, steel is not) [ETA: comment below points out brass not ok]
light switches
faucets
toilet handles
refrigerator
drawer handles
writing implements
backs of chairs
Depending on how many people you are sharing touch-space and not air-space with, I expect covering these in copper could reduce infection by anything from 1 to 50%, though I expect in a typical house of four people who sometimes venture outside and don’t know about never touching your face, you’d get an effect roughly between 15 and 40%.
[UPDATED, thanks to various people who caught errors in V1 and pointed out V2] New NIH study of COVID half-life in aerosol or on surfaces V1 with errors: https://medrxiv.org/content/10.1101/2020.03.09.20033217v1 , V2 hopefully error free: https://www.medrxiv.org/content/10.1101/2020.03.09.20033217v2.full.pdf (H/T @AndyBioTech)
2.4-5.11 hours on copper, in contrast to 10.5-16.1 on steel or 13-19.2 on plastic
This study describes “detecting viable virus” as having a threshold of 10^0.5 TCID50/mL, and they assume exponential decay of viable virus particles.
I’m really confused by their numbers, tho; it looks like cardboard has a hundred-fold reduction in 23 hours, from 10^2.5 to their detection threshold of 10^0.5, which I can’t square with the 8.5 hour half-life. [Edit: it looks like I’m potentially confused about what TCID50/mL means?]
I also don’t know how to compare their detection threshold with the point at which I should be willing to handle a cardboard box (with varying levels of cleaning and PPE). Is their test basically as sensitive as my immune system (in that I shouldn’t handle something where they could see a viable virus, and can handle something where they can’t)? Or should I be letting boxes sit for 3 days?
I had the same confusion over the half life ratings.
TCID50/mL is how much you can dilute a sample and still have it kill half of the cells in a sample. This suggests that the natural reading of those graphs is correct.
I estimated some numbers off the graph and it looks like what they are calling half-life is actually 1/5th life, so either we’re both missing something important or there is an error somewhere.
I’ve emailed the author; we’ll see if she has time to respond (or if the code goes up on Github; I can’t find it yet).
Looks like v2 of the paper has corrected the error.
See here: https://www.lesswrong.com/posts/B9qzPZDcPwnX6uEpe/coronavirus-justified-practical-advice-summary?commentId=LuJRfhrNhu4aBanQn
Worth noting that a lot of metal handles will be coated with a finish that prevents you from actually touching the metal. This is because these metals (especially copper) can leave a strong metallic smell on your hands which people typically dislike, and also because it prevents the metals from tarnishing. These handles will not help reduce infection and will need copper tape on them.
Killing bacteria isn’t the same as killing viruses. Do we have reason to expect the same efficiency?
Sorry, forgot to modify this for a virus-specific claim, but yes.
On solid copper, H1N1 decreased by 4 logs in 6 hours in this review; vaccinia and monkeypox viruses were reduced by 6 logs in 3 minutes in this study; murine norovirus was destroyed in 30 minutes in this study, though it doesn’t work very well at 4C; and another review says that copper oxide filters neutralize all of “bacteriophages [58-62], Infectious Bronchitis Virus [63], Poliovirus [61,64], Junin Virus [59], Herpes Simplex Virus [58,59], Human Immunodeficiency Virus Type 1 (HIV-1) [11,65-67], West Nile Virus [11], Coxsackie Virus Types B2 & B4, Echovirus 4 and Simian Rotavirus SA11 [68]. More recently, the inactivation of Influenza A [55,65], Rhinovirus 2, Yellow Fever, Measles, Respiratory Syncytial Virus, Parainfluenza 3, Punta Toro, Pichinde, Adenovirus Type 1, Cytomegalovirus, and Vaccinia [65]”.
In this context, is a log a factor of 2, or of 10 (or of e)?
Medical doctors, so 10
Wikipedia suggests copper can kill at least influenza A virus and adenovirus. It seems likely that it would be effective against other viruses too, though not clear (to me) if it would work against every virus.
This ERI review concludes that there was really only one RCT (the one you linked), and they found that the study didn’t actually reach significance
What’s going on here is that Salgado splits outcomes into 4 groups, nothing, infection, colonization, and both, and finds a difference between the 4 groups. The review says “I only care about infection” and compares infection vs non-infection, and finds no significance. Each version of their math checks out, but I’m inclined to trust the review here.
This quasiexperimental study found similar decreases in infection rates however.
I’m not sure how to evaluate this evidence, but I’d be cautious about taking the Salgado results on its face.
If it’s a cheap countermeasure that aims, in the better estimate, for a 50% reduction of a small risk I think you’d be better off asking yourself if you’d buy it at double price rather than deciding which of the equally persuasive, conflicting experimental evidences about its efficacy you should trust. Also if you’re worried about non monetary costs like hand skin damage, I guess you’d better decide if you’d put up with the same cost for a 25% risk reduction.
Earlier I heard something like “wrinkles in the copper can reduce the effect, something something the fluids get caught in little pockets and leave spots that don’t touch the copper.”
Have you heard anything about that and have any thoughts on that? A lot of the images I see of people coppering their doorknobs are particularly wrinkly, and I’m wondering how much effort to put into getting everything smooth.
Not that it’s necessary to make this comment complete, but I’d love to hear more about that 50% estimate. I’ve had a very hard time getting data on that.
+1
Do you expect this to work for copper that has oxidized? Our bathroom copper is turning green and not sure if it’s still doing anything.
Oxidized copper has actually shown*increased* anti microbial activity in some studies IIRC. Also this https://www.sciencedirect.com/science/article/pii/S0010938X17313963
Is there a reason we’re not spamming reddit/discords etc. with this advice?
I don’t have enough karma on reddit to do things, but r/china_flu, r/lifeprotips, r/todayilearned all seem like good places to post this information.
Additionally, it might be worth it to spam amazon listings of copper tape with reviews saying it has antiviral properties. Possibly contacting the sellers of the tape as well.
Because ‘spamming’ is a rude way to force people to pay attention to you, and should be discouraged. But posting the information in ways that follow community norms seems good, although I’d want to think a bit about prioritising messages to spread—quite plausible to me that advertising the need for expanded capability to supply oxygen to people is more important.
Note that sellers probably can’t make claims about this without running into legal tape.
The document referring to copper that I found via SSC was https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3067274/ .
The time of contact killing listed among the different microbes ranges from 1 minute to over a week. I don’t know which example of a microbe would be closest to copper.
One big problem that may exist with using copper that I came across is that copper may reduce in efficacy if it is frequently cleaned, whereas stainless steel is fine to repeatedly clean. Source
The cleaner suggested to be used on copper surfaces without reducing its efficacy by this paper .
That seems useful. You forgot one of the most commonly touched items—phones and computers. I am gonna put tape on the back of my phone case and my laptop.
This is a good point, but for what it’s worth I don’t fully endorse coppering your phone (mine isn’t coppered). Several people have anecdotally reported it being uncomfortable or irritating on their hands, or receiving tiny cuts from the copper, etc.
Absorption through skin is incredibly low, but I do take the risk of open (if tiny) hand wounds seriously, and also generally try to reduce my total copper contact in case anything weird does happen, since this is not tested by time.
Some discussion of whether wearing copper jewelry causes unsafe exposure to toxic copper compounds:
https://orchid.ganoksin.com/t/verdigris-poisonous-copper-compounds/42591
Seems like the case for copper on door handles is stronger than the case for copper on your phone, laptop palm rests, etc.
You touch these often, yes, but how often do you share them with other people? If all the germs on there are yours, maybe disinfecting it is not really helping.
But if you are constantly handling your phone it will reduce the value of frequent washing/sanitizing of hands, since anything you do get on your hands will transfer to your phone.
Although, I don’t know what the numbers look like for transferring virus when a touch occurs—e.g. if we look at a path like “handshake → touch phone → [wash hands] → touch phone → touch face”, how much of the virus is left after four sequential touch events like that? Perhaps this kind of secondary contamination is not actually a huge deal? I have no idea.
I guesstimate the deal is not negligible.
Input to my intuition:
(source http://theconversation.com/atms-dispense-more-than-money-the-dirt-and-dope-thats-on-your-cash-79624 )
A powder called Glo Germ, meant to visualize germ spread, was still visible to the naked eye after 8 handshakes (but not 9) in an informal experiment by YouTuber Mark Rober. ( https://youtu.be/I5-dI74zxPg?t=346 )
This is my usual attitude, but given the evidence that coronavirus is very long lived on surfaces and reinfection is possible, it seems worth it to me in this specific case.
Living in a group house? Consider copper tape on:
Front door handle
Bathroom door handle and sink handle
Refrigerator Door handle
Kitchen trash lid handle if not touchless
Microwave handle + small square of cutout copper tape on ‘+1 minute’ microwave button