Viruses didn’t become ubiquitous by being wimps: From the rhinoviruses that cause the common cold to the new coronavirus that has spread across the world, they are able to survive on surfaces far away from the living cells that they need in order to reproduce.

How long they can lurk before a living organism comes along to infect depends on the kind of surface and the properties of the virus: The Covid-19 virus, according to a new study, sticks around on plastic surfaces for up to three days, but for a shorter period on metals.

Rhinoviruses can survive on human skin for hours, which is why shaking hands with someone who has a cold is a good way to catch it. Influenza viruses remain infectious for up to 48 hours after landing on nonporous surfaces such as stainless steel or plastic such as that in computer keyboards, but that seems like the outer limit: A 2011 study found that the H1N1 flu virus that caused the 2009 pandemic could be recovered from glass, stainless steel, plastic, and aluminum for up to 48 hours, but most was gone after nine hours. Both cold and flu viruses survive for much shorter times on porous surfaces such as cloth, paper, or tissue, with very little infectious virus remaining after four hours.

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Viruses covered in “envelopes” have the most trouble surviving outside a living cell. On surfaces, the surrounding light, heat, and dryness break down the envelope, killing the virus. (Porous surfaces pull moisture away from viruses that land on them, accelerating the destruction of the envelope.) Most rhinoviruses have such envelopes; so do some influenza viruses. Norovirus doesn’t, enabling it to last longer in the environment.

Then there’s the new coronavirus. Its survival on surfaces is similar to that of the SARS virus, to which it’s related. On plastic, after eight hours only 10% of what researchers deposited was still there, according to a study published on Tuesday in the New England Journal of Medicine. But the virus didn’t become undetectable until after 72 hours. On stainless steel, the numbers began plummeting after just four hours, becoming undetectable by about 48 hours. On copper and cardboard, virus was undetectable by eight hours and 48 hours, respectively.

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The fewer the virus particles on a surface, the lower the chances that someone touching it will become infected. “You have to get a certain level of virus exposure to be infected,” said Ross McKinney, chief scientific officer of the American Association of Medical Colleges. And infection cannot happen through the skin: to “self inoculate,” one must transfer virus from, say, the fingers to the nose or eyes, where it can enter the body via mucus membranes.

But because the virus that causes Covid-19 is, like other microbes, so durable, thoroughly washing hands after touching surfaces that anyone else might have touched — or not touching them in the first place — is the first line of defense against infection.

  • What about a 190F sauna for 25 – 30 minutes a day. Can anyone say if this would have a positive effect on the virus should someone be incubating ?

  • If buy and refrigerate objects such as vegetables with corona virus deposits, how long can that virus survive in refrigerators??

  • I’m a non-scientist/non-expert and was grateful for this article when I first read it, because it gives clear guidance about something we’ve all been worried about.

    However, last night, I read some Facebook posts and comments by Dr. Otto Yang (a researcher and clinician specializing in infectious disease at UCLA) that raise questions about the accuracy of the research this article is based on.

    In one post, someone asks him, “Is the current lifespan of the virus on surfaces still three days?” He responds, “One study suggests that but I think it’s unclear and highly variable, probably much shorter.”

    (link to that exchange: https://www.facebook.com/ahorejsi/posts/10158493694520362)

    In another comment, he provides a “Cliffs notes” summary of what he sees as the flaws in the study: “This paper is a model in the lab. They took a huge amount of virus and made an artificial aerosol. These conditions don’t reflect reality. They concluded that the original SARS and this new SARS-CoV-2 are both equally capable of aerosol spread, but this contradicts what is known about SARS; it was studied extensively and found NOT to be aerosol spread. So the conclusion about SARS-CoV-2 can’t be trusted either.”

    Due to privacy settings, I can’t provide a link to the post where he left the comment above. But here’s a link to a longer post he wrote (reposted by another Facebook user) explaining why the results of the “72 hours” study are questionable: https://www.facebook.com/groups/californiatracker/permalink/2872228599482278/?hc_location=ufi

    One of the points he makes often in his writing is that non-scientists need to be careful about what we read and share online, because we’re all hungry for answers, so when we come across something that seems to offer us certainty, we latch onto it and start treating it like it’s the truth — but often it’s just a theory, or there’s some kind of flaw in the underlying reasoning. His advice on this is never to trust any one individual source (including him!) — always check multiple sources.

    In terms of how long the virus lives on surfaces, in questioning the “72 hours” study he’s not advocating that we carelessly assume that the virus quickly decays. He writes, “…people are citing very detailed exact numbers…. We don’t know, but it’s moot. Who cares? Treat every surface like it could have virus. Again, bleach or lysol-type wipes and sprays are extremely effective.”

    If you’re looking for a careful, thoughtful voice on this topic who explains things in a way that non-experts can understand, look up his posts, I’ve found them to be a huge help.

  • This video was very helpful, thanks for putting this video out because it was very helpful because I didn’t know nun of the things that was in this video.

  • One could wear gloves if they are going to be in an area of possible Covid-19 infection. One could also carry some alcohol wipes and wipe the surface to be touched or their own hands. Being practical and prepared always helps.

  • Can one disinfect, kill coronavirus, on a surface by heating it with a heat gun or hot air hair dryer?

    • If you can heat a surface to 150 degrees Fahrenheit without destroying it, probably. You’d also have to make sure you’re actually getting it hot enough.

  • Hello,
    I have a 40 yr old son who is by far scared to death of the Coronavirus. He will not even go to the grocery store. What can I do? I am 66 yrs. old and I am not as paranoid as he is. He seems to think that if you pass by someone who has the virus you will catch it. Now, I think that if a person sneezes or coughs in your direction and you are too close, then yes, it is a possibility. Or if you kiss someone on the mouth who has the virus, then that is another possibility. I have a compromised immune system from Hepatitis C (although cured), so I think I could get it easier, but I am the one going to the grocery store. I don’t mind, because its a virus, I am in pretty good health for my age so we do have to eat, so you go to the store. I just don’t pick up produce that has been picked at, and if I do I wash it immediately when I get home. Just be careful, that is all we can do.

    • This same study in another article says the virus can stay in the air up to 72 hours. So your son isn’t too paranoid.

    • Sounds like your son has OCD – just like me! I hope he can find effective therapy through ERP (Exposure and Response Prevention) once all this excitement dies down.

    • It appears that you have misread the study. The virus doesn’t stay viable in the air for 72 hours. It can be viable for up to 72 hours on certain surfaces. It will not hang about in the air for three days, so it’s impossible to walk through a “cloud” of COVID19 2-3 days after someone sneezed or coughed.

  • Hi. Great piece. Very helpful info. I’d like to share this but have a question: The write-up accompanying the charts in the appendix to the NEJM piece refers to the dashed line in the titer of viable virus plots as “the limit of detection,” but does it definitely follow that undetectable = not infectious? Not a scientist, looking for guidance here!

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