The narrative is that the virus stays alive for up to three days on surfaces. My understanding of viruses like this would make that an extreme outlier. Do we have any conclusive data on the duration of virus viability outside of the host?
Detectable in aerosols for up to three hours. Up to four hours on copper. Up to 24 hours on cardboard. Up to three days on stainless steel and plastic.
Yeah, the gap between the two is measured in luck.
More serious answer, I wouldn't tempt any of these figures by trying to cut them short. I've yet to see any research on minimum for infection related to SARS-CoV-2 (such that you can run that against the declines on surfaces like eg plastic, instead of waiting the full 72 hours).
The dashed lines in that visual indicate the limits of detection for the surfaces. There is still some virus likely to be remaining beyond these detection limit times, however it wouldn't be believed to pose a risk of infection at those levels. For example some trace amount of the virus is likely to remain on plastic up to 80+ hours. And absolutely none is expected to still be on copper after 20 hours.
The "better safe than sorry" advice is fine if your goal is to avoid getting the virus at all costs. Many people feel that way right now, but complacency will set in eventually.
As a relatively young and healthy individual, I'm already not worried about avoiding the virus for my own wellbeing. If I get it, I will probably show mild symptoms and make a full recovery in a few weeks without needing any medical care. I'm not afraid of getting it, but I do want to take reasonable precautions to avoid spreading it to those at much greater risk.
Most of the public, myself included, are not going to build decontamination stations in their houses. Frankly, that's too much effort for too little personal benefit. If we understand how the virus spreads and use that knowledge to encourage more efficient precautions, then we'll ultimately do a lot more good.
That's why it's important for us to paint an accurate picture of how effectively it spreads on inanimate objects. If the message is just "better safe than sorry", most people will eventually decide to take their chances.
I've been using it to disinfect supplies I bring home and don't want to quarantine for a day before bringing inside, as well as washing my hands.
Is there a reason it's not mentioned? Am I misinformed on its effectiveness as a disinfectant vs. viruses?
It's always been my goto for disinfecting surfaces... it's nice in that it decays into harmless water, and it's not really an issue if you get small quantities of 3% in your mouth, even if swallowed.
Have a look at the "Many common household disinfectants" recommendation. It links to an EPA page, which has a lot of Hydrogen Peroxide-containing products that should work.
Hydrogen peroxide is excellent for many viruses, including coronaviruses. There's a "new" generation of disinfectants based on hydrogen peroxide (search for Clorox or Diversey brand) and they list a 30 second contact time for human coronavirus inactivation. It's an oxidizer like bleach, but like you said degrades to water and oxygen, making it safe and residue-free. I use it regularly to disinfect lab equipment that would get destroyed by bleach.
This is stupid, it's a respiratory virus, it needs to enter your lungs. Get your stuff, wash your hands. Done. This is why restaurants are still open for takeout.
> This is stupid, it's a respiratory virus, it needs to enter your lungs. Get your stuff, wash your hands. Done. This is why restaurants are still open for takeout.
Why is washing your hands appropriate but not washing the contaminated items you'll touch with your washed hands afterwards?
Sadly, it's not entirely clear that washing hands makes a difference either. It might, but it also might not. Michael Ostermholm, director of CIDRAP, explained, 'One of the things, people want to do something. They want to feel like they’re doing something, and so we tell them, “Wash your hands often to prevent this disease.”' [0]
There has been one study showing that SARS-CoV-2 can remain viable, albeit exponentially degraded, for 72 hours on certain hard plastics or metals, in ideal conditions in a laboratory. [1] So there's that.
We don't know whether fomite transmission is possible yet. It's probably not the best idea to spend a lot of time or mental anguish scrubbing and sanitizing everything, but obviously simple easy steps like washing hands with non-antibacterial soap can't hurt.
I assumed the wash your hands thing was so that when you inevitably touch your face you’ll do so with cleanish hands and avoid depositing the virus near your nose or mouth where it could then go to your lungs.
Cause you may put your finger in your nose or rub your eyes but you won't do that with the food containers. If you wash your hands which came in contact with the food and its container after eating and avoid touching your face while eating your food then you don't deliver any viruses to your respiratory system.
I have not seen any evidence showing that the virus must directly enter via the lungs to be transmitted. Every authoritative source I've seen recommends taking precautions from transmission via surfaces as well.
There's a lack of evidence in general. That FAQ makes the same points as the OP does -- that the risk of infection via food and/or surfaces is low, but possible.
And someone else in your household picks up one of those items a couple of hours later (not knowing it only recently arrived via delivery) and touches their eyes, mouth or nose...
I wonder if the "dilute to 70%" rule for isopropyl applies to coronavirus. My understanding is that you dilute 99% because you need the water to catalyze action on bacterial cell walls. But that wouldn't apply to virions.
It's my understanding that its also necessary to dilute to slow down the evaporation rate. At above 90%, it simply evaporates too quickly to have effect.
Doesn't it also denature proteins very quickly at 99%?
(I ask because I worked a polling precinct on Tuesday and 99% isopropyl was how I disinfected the smartcards that unlocked the BMDs for voters and then got passed back to us; it definitely did not evaporate instantly on those cards).
I'd be interested in knowing whether anyone with expertise on this subject has thoughts on it. The boy is a biochem junior (and in my living room, because of coronavirus) and he doesn't have a firm answer on whether it would or wouldn't work.
I got word back from a infection disease pathobiologist (through her husband, a friend): 70% for surfaces, because it takes longer to evaporate, 99% for instruments.
I understand it to matter a great deal when you're trying to get rid of bacteria, but it is a little tricky to square with the "we use 70% for surfaces and 99% for instruments" thing I got from the professional.
It may have something to do with the lipid layer around covid-19 that isn't necessarily shared with all other viruses. Supposedly the lipid layer breaking down is why soap works so well
Where are the references? What concentration bleach?
From TFA: "Unfortunately, bleach solutions need to be made fresh every day"
From CDC[0]: "If chlorine solution is not prepared fresh daily, it can be stored at room temperature for up to 30 days in a capped, opaque plastic bottle with a 50% reduction in chlorine concentration after 30 days of storage (e.g., 1000 ppm chlorine [approximately a 1:50 dilution] at day 0 decreases to 500 ppm chlorine by day 30)."
As I understand it, chlorine loss is not a first order process like this. The more concentrated the solution, the shorter the half life.
It may well be that there is a first order effect as well, and the 30 day half-life is a conservative estimate when diluted with worst-case impurities in tap water.
I'm curious how this applies to the bleach sold in stores. Are they doing something to make that last longer? Otherwise it sounds like they should be treating it with perishability similar to milk.
A few things here are worth noting. Highly pure bleach is more stable. And chlorate is undesirable and mildly toxic. You don’t want too much in your drinking water.
From experience, one should only buy bleach from stores with decent turnover. Bleach from the corner store may well be dead.
Good questions and I'm curious on the actual science too.
We're using liquid pool chlorine diluted with water -- pool chlorine is just higher-concentration bleach.
Although not scientific by any stretch, I know that the general guidance (and my experience from chlorinating & testing pools) is that you want to check the dates on the chlorine when purchasing because the strength can be substantially lower than stated if it's been sitting on the shelf for a long time. My understanding is that the effect is worse if the product has been sitting outside in direct sunlight / high heat (ie outdoors at a home improvement store), which I believe causes concentration to drop faster.
If you're having trouble finding bleach though, likely can get some at a pool store or a big-box home improvement store in the pool chemicals area. We just mix it down to suitably diluted concentrations in a spray bottle -- readily available & much cheaper than off-the-shelf spray products. I wasn't aware it might be 50% lower concentration in 30-days though, will have to re-mix ours here soon. But that's still small potatoes overall, a gallon of bleach goes a long way and has lots of uses. :)
Is decontamination really necessary? Can't you just ensure that you wash your hands after handling any delivered goods.
For example, after receiving a delivery of something, you wash your hands after opening it. After receiving a food delivery, you heat the food and again wash hands before eating. Is this not sufficient?
Many delivered foods are eaten from the same containers they are delivered in, and many of those containers can't themselves be heated. (plastic doesn't get hot in the microwave and melts in an oven)
You could maybe transfer it to a metal container first?
This has been on my mind periodically today because I ordered takeout for lunch for the first time in a couple weeks. Aside from not all takeout foods requiring to be heated thanks to wider options from services like Favor and Uber Eats (deli sandwiches, sushi, salads, etc...), quite often it's food eaten with your hands out of disposable containers/packaging handled by someone else, rather than utensils preventing additional touching of the packaging it came in.
You can't, that's the point. Take all the precautions you want, but it's just impossible for some things (sushi also included). It's not like you can wash bread either.
You don't get infected by eating it even if it's contaminated though. At least there is no evidence that you can get a respiratory infection by eating the virus.
I have yet to find clear guidance on how to handle perishable food that belongs in my refrigerator or freezer and cannot be left out on its own for a day or two if I lack the cleaning products recommended in the article. Does anyone have any reference material on whether "isolating" such things in my fridge for a period of time might be effective?
Isn't the article forgetting the biggest factor: The human delivering your food?
They will be delivering for hundreds of people and may well be infected. Do you need to hide behind the door and ask them to leave it there and hand them a tip somehow. Because holding a 6 feet distance while they hand you your grocery/food is not gonna work.
I asked the same from the delivery guy Yesterday, he threw everything he had and run away like I had the plague :D. So be careful.
One of the food delivery apps available where I live initially started offering no-contact delivery as optional, after a few days no-contact was default and I think now it's the only option for delivery.
You can't fully reduce the risk from aerosol, as who says that in an apartment building someone didn't pass by 5 minutes before and went all disciple of Nurgle by coughing their lungs out, but that is that.
62 comments
[ 3.5 ms ] story [ 116 ms ] threadThe visuals:
https://www.nejm.org/na101/home/literatum/publisher/mms/jour...
The study (published March 17):
https://www.nejm.org/doi/10.1056/NEJMc2004973
More serious answer, I wouldn't tempt any of these figures by trying to cut them short. I've yet to see any research on minimum for infection related to SARS-CoV-2 (such that you can run that against the declines on surfaces like eg plastic, instead of waiting the full 72 hours).
The dashed lines in that visual indicate the limits of detection for the surfaces. There is still some virus likely to be remaining beyond these detection limit times, however it wouldn't be believed to pose a risk of infection at those levels. For example some trace amount of the virus is likely to remain on plastic up to 80+ hours. And absolutely none is expected to still be on copper after 20 hours.
As a relatively young and healthy individual, I'm already not worried about avoiding the virus for my own wellbeing. If I get it, I will probably show mild symptoms and make a full recovery in a few weeks without needing any medical care. I'm not afraid of getting it, but I do want to take reasonable precautions to avoid spreading it to those at much greater risk.
Most of the public, myself included, are not going to build decontamination stations in their houses. Frankly, that's too much effort for too little personal benefit. If we understand how the virus spreads and use that knowledge to encourage more efficient precautions, then we'll ultimately do a lot more good.
That's why it's important for us to paint an accurate picture of how effectively it spreads on inanimate objects. If the message is just "better safe than sorry", most people will eventually decide to take their chances.
I've been using it to disinfect supplies I bring home and don't want to quarantine for a day before bringing inside, as well as washing my hands.
Is there a reason it's not mentioned? Am I misinformed on its effectiveness as a disinfectant vs. viruses?
It's always been my goto for disinfecting surfaces... it's nice in that it decays into harmless water, and it's not really an issue if you get small quantities of 3% in your mouth, even if swallowed.
Why is washing your hands appropriate but not washing the contaminated items you'll touch with your washed hands afterwards?
Your comment strikes me as stupid.
Sadly, it's not entirely clear that washing hands makes a difference either. It might, but it also might not. Michael Ostermholm, director of CIDRAP, explained, 'One of the things, people want to do something. They want to feel like they’re doing something, and so we tell them, “Wash your hands often to prevent this disease.”' [0]
There has been one study showing that SARS-CoV-2 can remain viable, albeit exponentially degraded, for 72 hours on certain hard plastics or metals, in ideal conditions in a laboratory. [1] So there's that.
We don't know whether fomite transmission is possible yet. It's probably not the best idea to spend a lot of time or mental anguish scrubbing and sanitizing everything, but obviously simple easy steps like washing hands with non-antibacterial soap can't hurt.
0: https://www.rev.com/blog/transcripts/joe-rogan-michael-oster...
1: https://www.nejm.org/doi/full/10.1056/NEJMc2004973?query=fea...
It's just not 100% clear whether this form of transmission is actually possible.
The surprising part to me is that Osterholm was so candid on the topic.
(I ask because I worked a polling precinct on Tuesday and 99% isopropyl was how I disinfected the smartcards that unlocked the BMDs for voters and then got passed back to us; it definitely did not evaporate instantly on those cards).
I'd be interested in knowing whether anyone with expertise on this subject has thoughts on it. The boy is a biochem junior (and in my living room, because of coronavirus) and he doesn't have a firm answer on whether it would or wouldn't work.
From TFA: "Unfortunately, bleach solutions need to be made fresh every day"
From CDC[0]: "If chlorine solution is not prepared fresh daily, it can be stored at room temperature for up to 30 days in a capped, opaque plastic bottle with a 50% reduction in chlorine concentration after 30 days of storage (e.g., 1000 ppm chlorine [approximately a 1:50 dilution] at day 0 decreases to 500 ppm chlorine by day 30)."
[0] https://www.cdc.gov/infectioncontrol/guidelines/disinfection...
It may well be that there is a first order effect as well, and the 30 day half-life is a conservative estimate when diluted with worst-case impurities in tap water.
A few things here are worth noting. Highly pure bleach is more stable. And chlorate is undesirable and mildly toxic. You don’t want too much in your drinking water.
From experience, one should only buy bleach from stores with decent turnover. Bleach from the corner store may well be dead.
We're using liquid pool chlorine diluted with water -- pool chlorine is just higher-concentration bleach.
Although not scientific by any stretch, I know that the general guidance (and my experience from chlorinating & testing pools) is that you want to check the dates on the chlorine when purchasing because the strength can be substantially lower than stated if it's been sitting on the shelf for a long time. My understanding is that the effect is worse if the product has been sitting outside in direct sunlight / high heat (ie outdoors at a home improvement store), which I believe causes concentration to drop faster.
If you're having trouble finding bleach though, likely can get some at a pool store or a big-box home improvement store in the pool chemicals area. We just mix it down to suitably diluted concentrations in a spray bottle -- readily available & much cheaper than off-the-shelf spray products. I wasn't aware it might be 50% lower concentration in 30-days though, will have to re-mix ours here soon. But that's still small potatoes overall, a gallon of bleach goes a long way and has lots of uses. :)
It seems like a good idea to reheat food to 165F (74C) which is likely sufficient to deactivate the virus.
For glass, metal, and plastic, as well as vegetables, soap should be fairly effective.
You could maybe transfer it to a metal container first?
Salad not so much.
You then put the lettuce in a spinner to get most of it off. Then you wait a while for most of the rest to evaporate.
We have clean water so I expect we can use clean water to rinse the bleach off.
They will be delivering for hundreds of people and may well be infected. Do you need to hide behind the door and ask them to leave it there and hand them a tip somehow. Because holding a 6 feet distance while they hand you your grocery/food is not gonna work.
I asked the same from the delivery guy Yesterday, he threw everything he had and run away like I had the plague :D. So be careful.
You can't fully reduce the risk from aerosol, as who says that in an apartment building someone didn't pass by 5 minutes before and went all disciple of Nurgle by coughing their lungs out, but that is that.