The Scientific Facts about Sanitizing Surfaces: Package Deliveries, Groceries, Mail, etc.

(Posted March 30, 2020)

Can I get infected by COVID-19 from the mail? From packages and other deliveries to my home? From the food and packaging of groceries I buy at the store or friends bring to me or that are delivered to me?

We are hearing questions like this, as well as questions about disinfecting surfaces in one’s home, especially often touched ones like door knobs, light switches, hand rails, and kitchen counters.

And what about towels, toothpaste and other possibly shared household items, clothing (especially gloves)?

The good news is that the odds of becoming infected by surface-borne COVID-19 are small and relatively easy to make much smaller, as you will read below.

Sources: 
Much of what follows is based on an article written by Joseph G. Allen, assistant professor of exposure and assessment science and director of the Healthy Buildings Program at Harvard University’s T.H. Chan School of Public Health, entitled Don’t panic about shopping, getting delivery or accepting packages, The Washington Post, March 26, 2020. 

Some additional sources, some of which may be of interest to readers:
Unfortunately, some of the above articles appear in online publications that have a “pay wall,” which may allow only limited or no viewing to people who are not paying subscribers. We sincerely hope that during this emergency most media organizations will soon provide free access to COVID-19 related articles.

What does the science of disease transmission tell us about the likelihood that we might become infected by a virus like COVID-19 simply by touching objects that might have the virus on them? 

Note: You may want to skip this explanation of how the virus is transmitted and go straight to advice on how to reduce even the smallest odds of infection from surfaces; however, if you are stressed out and fearful about this matter, you may want to read this explanation of the science first. It isn’t hard to understand and it should comfort you.


The Science of Virus Transmission with a Focus on COVID-19

First, a brief lesson about how viruses like COVID-19 are transmitted to people. 
  • Viruses, although not truly alive, are similar to certain living parasites: in order to carry out the functions of a living organism, in particular reproducing themselves, they need to be inside the cells of a host such as a human or certain other animals.
  • Because, unlike bacteria, viruses cannot reproduce outside of a host cell, they can’t multiply and spread out on an inanimate surface.
  • Similarly, because viruses are not truly alive, they cannot move around on their own, meaning that any COVID-19 on an inanimate surface is likely to be on only the part of the surface where they were initially deposited and can only be transferred to a person if their fingers touch that particular area.
  • Once outside a host cell, viruses like COVID-19, degrade rather quickly; depending on the surface, significant degradation may take place in a matter of hours and, generally speaking, the amount and viability of a deposited virus on a surface drops to extremely low levels within a few days.
(These figures for COVID-19 survival on surfaces come from scientific studies, based on controlled laboratory tests, and reported in an article written by scientists from the National Institutes of Health, CDC, UCLA and Princeton University and published in the highly-regarded peer-reviewed New England Journal of Medicine. *See footnote at end of this post for an in-depth discussion of virus viability over time.)
  • The COVID-19 virus appears to be entirely water-borne (in saliva and mucous); according to Hartford Healthcare:  Coronavirus can’t go anywhere without a droplet of saliva or mucus.” (This is in contrast to the transmission routes of many other familiar viruses such as those associated with measles, mumps, chicken pox, polio, shingles, hepatitis, and AIDS).
  • Thus, any COVID-19 virus that might be present on an inanimate surface like a package, milk carton, or bag of oranges most probably got there directly from virus-containing water droplets in the sneeze or cough of someone who handled those goods and not from their momentary touch. 
  • Ultimately, in order for a person to become infected by COVID-19, the virus must enter the person’s respiratory system. 
  • Infectious disease experts like Dr. Anthony Fauci, Director of the National Institute of Allergies and Infectious Diseases, express certainty that by far the primary way that COVID-19 enters the respiratory system (where it does its damage) is for a person to inhale virus-laden water droplets directly from an infected person’s sneeze or cough. (We strongly recommend viewing this 15 minute clip of Anthony Fauci being interviewed by Trevor Noah; it addresses not only this issue, but almost every other question you may have been asking about COVID-19.)
  • Another, but far less common way, for the relatively large COVID-19 virus to be transmitted (although fairly common for lighter-weight viruses) is for a person to sneeze, cough, or (believe it or not) talk or laugh in such a way that a very fine aerosol of the virus remains suspended in air, even after the carrier has left the room, elevator, or other confined space. Then, along comes an unsuspecting person (perhaps someone in a higher risk category) and breathes in the virus aerosol.
  • Once again, infectious and viral disease experts like Dr. Fauci, are quite certain that compared to either of the above two water-borne ways for COVID-19 to get into a person’s respiratory system, the transmission from an inanimate object is much less likely. 
  • And here’s the one final point: even if COVID-19 viruses do get on to a person’s fingers, in order for that person to actually become infected, they would have to touch themselves in places that are routes to their respiratory system (eyes, noses or mouths) with the finger(s) carrying the virus, and to do so prior to washing their hands (correctly). 
Let us now apply the above understanding of the science of virus transmission to the question of how likely it is that we might be infected by mail, packages, or other items coming into our homes from the outside world.

What are the steps that would need to happen for you to become infected by COVID-19 from something you touch that comes into your home from the outside world ?

As you will see, there are at least five steps that would ALL need to happen in order for you to become infected by COVID-19 through touching something that is brought into your home, so that the likelihood of being infected in this way is actually quite small. 
  1. Persons handling the letter, package, or grocery item would have to be infected yet nevertheless be working, probably because they have had few if any noticeable symptoms.
  2. Those persons (carriers) would have had to cough or sneeze directly onto your package OR perhaps into their hand and/or wiped their nose or touched another surface already contaminated by another carrier’s cough or sneeze.
  3. And this person handling your package would have had to NOT wash their hands correctly between the time they got the virus on their hand(s) and when they may have touched your package, grocery item, etc. with the same part of their hand(s). 
  4. You would have had to touch the exact area on your package on which the virus was deposited and then, before washing your hands correctly, also touched your mouth, nose, eyes, or perhaps other parts of your face from which you might later pick up the virus.
  5. Finally, depending on how recently a virus may have been deposited on your package or produce, by the time it gets to your home, it will have degraded to some extent, possibly greatly, so that unless the delivery person sneezed or coughed on it shortly before bringing it to your house, there may be considerably less virus on the package than was deposited on it at its point of origin. 
The above scientific explanation is essentially why neither the CDC, nor the WHO, nor any other responsible public health agency has recommended that people sanitize the surfaces of packages and other materials coming into their homes. 

Indeed, there is NOT yet (to our knowledge) any scientific study or reliably documented case of persons becoming infected by COVID-19 merely by touching inanimate surfaces, no matter how much virus is subsequently found to have been on those surfaces.

On the other hand, there is irrefutable scientific evidence that by far the most common way for the COVID-19 virus to spread is through human to human transmission, which is why all public health agencies emphasize that everyone, especially those in higher-risk categories should adhere to guidelines like the following from the Vermont Department of Health:
  • Wash your hands often with soap and water for at least 20 seconds. If soap and water are not available, use an alcohol-based hand sanitizer.
  • Avoid touching your eyes, nose, and mouth with unwashed hands.
  • Avoid close contact with people who are sick.
  • Stay home and practice social distancing if you must go out. 
  • Cover your coughs and sneezes with your sleeve or a tissue, then throw the tissue in the trash and wash your hands.
  • Clean and disinfect frequently touched objects and surfaces. [Note: this is the only item in the list that may seem to be about something other than person-to-person transmission and perhaps even to contradict everything you have just read. Not so; the key words are “frequently touched.” Read on.]

What can I do to further reduce the likelihood of becoming infected by surface-borne COVID-19?

Wipe down surfaces in your home that are touched frequently like bathroom and kitchen faucets or light switches. 
The primary reason why responsible health organizations (like the Vermont Department of Health) make the recommendation to wipe frequently-used surfaces in your home is probably so we will all do whatever we can do easily to reduce the likelihood of becoming infected, especially those of us in higher-risk populations.

And because health officials are well aware that without the strictest adherence to quarantine and/or isolation, any of us at any time may become infected by COVID-19 through person-to-person contact with someone who is infected, although they might not seem to be or even know it themselves. So, if someone in our home does become infected, it is then possible that they might continuously deposit large amounts of the virus through frequent touching of surfaces that others in your household may touch and then touch their own faces. 

That is why, these organizations place so much emphasis on hand-washing, keeping 6’ away from others, and if you happen to work in situations where you have to greet others, take Anthony Fauci’s advice: “No shaking hands.” 

Other ways to further reduce the risks of infection from COVID-19 that may be on packages and groceries

Dr. Joseph Allen, the author of the article Don’t panic about shopping, getting delivery or accepting packages, provides a number of suggestions  along the following lines: 
  • Leave cardboard packages outside your door (or perhaps on your back porch) for a few hours or bring them into the house and leave them just inside your door; then, most importantly: wash your hands (correctly).
  • If you’re still worried, you can wipe down the outside of the package with disinfectant (an ordinary household cleaner works best) or open it outdoors and throw packaging into your recycling container. Then wash your hands...(correctly, of course).
  • Wait a while before unpacking and putting away non-perishable groceries; waiting even a few hours will significantly decrease the amount of any COVID-19 that might be on the surface of your groceries.
  • If you wish, you can wipe down the outside of any containers for dairy or other perishables, using your same disinfectant. Then...yes, wash your hands (correctly).
  • If you need to use any of your groceries right away, wipe them down or, in the case of fresh produce (even if they are organic), wash them thoroughly just as you would any non-organic vegetable or fruit that may have been sprayed with harmful insecticides. (The water you use can be cold, but, if possible, you should also use unscented soap and then rinse it off thoroughly.) Then… your turn to say it: ________
  • If you are in a higher-risk category, DO NOT GO TO A GROCERY STORE or for that matter into any business or store. If you need something, the best action to take for the sake of both your personal health and the public health of your community is to order by phone or internet and have your goods delivered. If such services are not available to you or you truly cannot afford them, then ask a friend or neighbor if they can get these things for you the next time they plan to go out to shop for themselves.
  • Even if you are not in a higher-risk category, yourself, if phone or online ordering and home delivery are available to you and you can afford it, the safest action for you personally and for the public health of your community is for you to order all your groceries and other necessities and have them delivered. Although it may seem counterintuitive, it is actually a better Public Health tactic for one delivery person to make a trip to a number of homes than for all those people to come into the store or to ask a friend/neighbor to shop for them. Home delivery is also safer for the front-line workers in stores that provide essential goods than having numerous people come into the store. And it does not put the delivery people at additional risk, as long as they follow personal safety guidelines. (Please include a tip in the online payment you made.)
  • And, of course when the delivery arrives and you handle it and eventually unpack it…. You know the drill. (Hint: it involves soap and water.)

Nevertheless, as Dr. Allen writes: 
We can never eliminate all risk; the goal is to minimize it...But, if you take basic precautions, including washing your hands frequently, the danger from accepting packages from a delivery driver or from takeout from a local restaurant or from buying groceries is de minimis. That’s a scientific way of saying, ‘The risks are small, and manageable.’

What about the YouTube video of that Michigan doctor that is taking social media by storm, which shows some ways to reduce the likelihood of you becoming infected by viruses on groceries and take-out packaging? 

Frankly, if all of the above information has calmed you down somewhat about the possibility of being infected by COVID-19 from packages and other things that come into your home, why would you want to get stressed all over again by watching this truly over-the top video by someone who is NOT an expert on infectious or other viral diseases? 

Moreover, you need to understand that this doctor's suggested procedure for handling groceries and deliveries is based on “sterile technique” which is designed for operating rooms, not ordinary homes (even in these extraordinary times). The video is pretty intimidating, unnecessarily so in our view, which is why we are deliberately NOT providing a link to it (not that this will stop some of you:). But, if you do find it and watch it, we urge you not to stress out as a result or to feel that somehow you are failing if you aren’t able to do what the video demonstrates. 

As even the doctor in the video says, “[just] do the best that you can,” which, in our view, is to follow the recommendations of the CDC, other responsible health authorities, and the governor of our state. 

Just as a reminder, the following is a somewhat edited and expanded list of those recommendations, compiled from a number of different reliable sources:
  • Avoid touching your eyes, nose, and mouth with unwashed hands.
  • Avoid physical contact with anyone who is or appears to be sick in any way.**
  • Cover your coughs and sneezes with your sleeve or disposable tissue, and then wash your hands.
  • Clean and disinfect frequently touched objects and surfaces in your home.
  • Do not travel, unless for an emergency, especially not for a long period of time in public transportation like a plane, train, or bus.
  • And, of course frequently and thoroughly wash of your hands (correctly)**
**NOTE: Many essential workers are likely to come in contact with COVID-19 carriers without realizing it. Such workers should speak with their supervisors about arranging for appropriate protections such as: N95 masks; disposable gloves; effective hand-sanitizer; provision for frequent hand-washing with soap, water, and paper towels; and, in the case of supermarkets and large pharmacies, there should be enforcement of the 6’ rule at all times and a transparent plexiglass or sturdy plastic physical barrier between cashiers and customers.

To repeat: by far the most common way for the COVID-19 to spread is through human to human transmission.



*Footnote: Discussion of virus viability over time OR what about the COVID-19 detected on cruise ships after 17 days?

If the NIH and other responsible research entities are reporting such short durations of time for viruses to remain viable on surfaces, what, then, about articles circulating widely in social media, citing a recent CDC report that includes mention of viruses being detected on surfaces in cabins on board several of the cruise ships with large clusters of infected people up to 17 days later?

Quite simply, these sensationalistic articles are, at best, misleading; their writers have ripped a brief mention of this factoid out of a CDC report entitled: Public Health Responses to COVID-19 Outbreaks on Cruise Ships — Worldwide, February–March 2020), which addressed the much larger issue of the well-established and highly problematic fact that: cruise ships are often settings for outbreaks of infectious diseases because of their closed environment, contact between travelers from many countries, and crew transfers between ships.” 

Moreover, not mentioned in these irresponsible media articles is the fact that the CDC report, itself, does not suggest in any way that this detection of the virus conflicts with prior controlled laboratory studies, nor does it invalidate conclusions about the very short amount of time COVID-19 viruses can generally survive on inanimate surfaces. 

The apparent discrepancy between the findings of the NIH study and the CDC report may be understood as occurring for a variety of reasons, including: the unique environment of cruise ships, which would likely have resulted in extremely large viral loads on cabin surfaces; the lack of any mention in either the CDC report or the media articles of just how much virus was “detected” or what "detected" might actually mean about its viability (e.g., the DNA of viruses can be "detected" long after the virus is no longer viable.) And, finally, it must be understood that non-controlled field reports like that from the CDC by their very nature always run the risk of failing to account for unknown, uncontrolled, potential causal variables such as: there is no way of knowing when or how the virus detected in cabins got on these surfaces; for example, it may have gotten on these surfaces from workers entering these cabins much more recently than when passengers left.

4 comments:

  1. nice formatting. Add the new information about using masks, if you agree

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    1. The new information about masks will be treated in an upcoming post entitled something like: "Social Distancing, Masks, Testing, and other Aspects of the Interconnectedness of Public Health and Personal Health ." We have suggested in several past posts that the public health messaging around masks was problematic, something the CDC is apparently about to change. Stay tuned.

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  2. Top notch! This has become my go to site for sorting things out for ourselves, thank you.

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  3. Thank you, Stuart. A high complement from someone I know to be a careful and skeptical reader :)

    ReplyDelete