How necessary is surface cleaning to prevent the spread of COVID-19?

July 20, 2020 9:29 AM

Much of the "re-opening plan" of various educational institutions I'm involved with includes mask wearing, some form of distancing, hand washing, and aggressive cleaning and disinfection of surfaces. The first two are based on sound science and there seems to be lots of evidence that they are effective. However, is there any evidence that vigilant disinfection of surfaces makes any difference in the transmission of the Coronavirus? How about hand washing?

It seems like a number of the "re-opening plans" spend a lot of space reassuring that the institution is doing everything they can to sanitize surfaces as often as possible. However, everything I've read about transmission of the Coronavirus seems to suggest surface-to-human transmission basically never happens. The only study I've come across is that one from March (?) talking about how long the virus lives on surfaces in ideal lab settings.

Is the focus on surface decontamination 1) based on real, sound science and has been shown to reduce transmission, 2) out of an abundance of caution because there's so much we don't know, or 3) an easy thing for places to say they're doing and a form of "Public Health Theater."

From my framing you can guess where my suspicions lie, but I'm interested in hearing if there is real evidence that surface decontamination (or even hand washing) reduces the spread of COVID-19.

posted by Betelgeuse to Health & Fitness (17 answers total)

One recent opinion piece in the Lancet calls the risk of surface transmission "exaggerated" and says, "Although periodically disinfecting surfaces and use of gloves are reasonable precautions especially in hospitals, I believe that fomites that have not been in contact with an infected carrier for many hours do not pose a measurable risk of transmission in non-hospital settings."
posted by pinochiette at 9:40 AM on July 20, 2020

There was a very accessible American Medical Association daily update about this from a week ago. Some choice quotes that I think answer much of your question:

"I think coronaviruses are not particularly hardy viruses in the environment, such that if they are on surfaces, disinfections and/or time on the surface quickly does make them less viable. So, despite the questions still out there, we think this is a respiratory virus mostly, and if there are some surface transmissions, disinfection is probably very effective at taking care of virus and reducing transmission from that route."

"Our hands are our way of interacting with the environment, and you asked questions about surface transmission and even surface transmission typically comes via our hands. And so it sounds like an old kindergarten adage, but "wash your hands" is still largely really good advice for us."

"And I think right now with COVID, social distancing is probably not 100%, but it's pretty good. Face coverings are probably not 100%, but they're adding another layer of protection. Being outdoors might be a way of adding a third layer to reduce risk. And so sometimes, when it seems we want to an easy fix for this pandemic, I don't think we have one, and therefore layering on the different strategies is really what will help us reduce transmission and hopefully keep more people safe."
posted by saeculorum at 9:57 AM on July 20, 2020

I have been watching this the whole time and have read exactly zero evidence that any case has resulted from touching an "infected" surface, or that surface decontamination does anything to prevent infection.

I do recall that in one of the sadder Florida bar superspreader events, the owner of the bar was quoted as being bewildered because he had made sure everything was so clean.

So, (2) and mostly (3).
posted by fingersandtoes at 9:58 AM on July 20, 2020

There was a study done on library materials that essentially said after one day the virus was undetectable on the covers of books and DVD cases, but traces of it could be found on the pages and on magazines for three days.

IMLS study - there's the link.

Which I guess doesn't necessarily answer your question in that because the virus is there, does that mean it can be easily transmitted to someone handling those materials? I'm not sure.

If nothing else, I think cleaning gives us some semblance of control.
posted by lyssabee at 10:11 AM on July 20, 2020

I heard a very recent talk by Dr. Fauci (which seems to have mysteriously disappeared from CNN) in which he placed heavy emphasis on person-to-person transmission, but included handwashing, not touching the face, disinfecting surfaces, etc as things to do. I suspect that there is an underlying assumption that these are things you do at all times to protect from colds, the regular flu, e coli, salmonella, etc, so they get included routinely.

No one that I've heard of has recommended that you totally disinfect your refrigerator once a week even though the virus could live indefinitely in the damp chill. I think the fridge would be a hot spot if surface contamination was a threat. This is totally an uninformed amateur's opinion, not expert advice.
posted by SemiSalt at 10:51 AM on July 20, 2020

I have 5 minutes or less between when a student in class 1 gets out of their desk and when a student in class 2 sits down. I know the virus will die exposed to the environment eventually, but is 5 minutes enough? Is it better to clean for no reason or not clean because early studies say it's (probably) not needed? Which one has more consequences if we choose the wrong one? Which choice can I live with if a student of mine dies?

Even if the studies say it's useless, I guarantee that if you don't do EVERYTHING possible a parent/customer will raise hell. Even if it's not necessary, institutions and corporations HAVE to do these steps just to protect themselves. So, maybe a bit public theater, but also a bit "we don't know what we don't know".
posted by rakaidan at 10:52 AM on July 20, 2020

Unfortunately, this unwarranted personal hygiene focus goes beyond theater and becomes a tool for blame deflection, particularly in workplaces. As long as it's possible to victim blame by suggesting that maybe the person contracting COVID-19 didn't take enough care in washing hands or disinfecting, it makes it easier for workplaces to avoid spending money on additional ventilation and additional space for distancing or avoid closing down if those aren't available.
posted by Harvey Byrd at 11:21 AM on July 20, 2020

Even if it doesn't affect covid at all, I am hoping that an increased focus on disinfecting surfaces and handwashing this year will mean that I might not get sick from all the typical germs that live in a school. Shhh, don't ruin this for me. I don't need more norovirus.
posted by lilac girl at 12:14 PM on July 20, 2020

I'm thinking it might be slightly more useful when there are groups of children involved.
posted by amtho at 2:44 PM on July 20, 2020

Another vote for 2 and 3. It's a respiratory virus - it's communicated through breathing, singing, talking, droplets in the air, hitting your lungs (and maybe eyes).

Food is unlikely to communicate it - your stomach kills the bugs. So unless someone really sneezes good on the table, then someone wipes their eyes enough to transfer stuff from the table into the eyes, and even then, the eyes are the least common mode of getting the virus. It's almost a sperm-level journey of the virus going up the tear duct, down the nose, and into the lungs.
posted by bbqturtle at 2:47 PM on July 20, 2020

There was this case of a superspreading event in China. Pull quote: "Researchers conclude the woman was an asymptomatic carrier who infected her neighbor via surfaces in the elevator."
posted by Mila at 3:57 PM on July 20, 2020

with regard to the China elevator case: recall that the CCP's stance, for months, was that the virus could not be transmitted by aerosol (tiny particles that hang around in the air, rather than being blown directly into a nose or mouth etc) transmission. So their researchers could not have admitted that transmission via the shared use of the elevator, or any vestibules or vents etc - were options, regardless of how much more likely that avenue looks based on the reported facts of the case.
posted by fingersandtoes at 4:16 PM on July 20, 2020

Pastorino B, Touret F, Gilles M, de Lamballerie X, Charrel RN. Prolonged Infectivity of SARS-CoV-2 in Fomites. Emerg Infect Dis. 2020 Sep. https://doi.org/10.3201/eid2609.201788 (Original Publication Date: June 24, 2020)

In conclusion, we showed that a moderate protein concentration in droplets markedly increased the infectivity of SARS-CoV-2, suggesting that a protein-rich medium like airway secretions could protect the virus when it is expelled and may enhance its persistence and transmission by contaminated fomites. Accordingly, it is plausible that fomites infected with SARS-CoV-2 play a key role in the indirect transmission of coronavirus disease (COVID-19). This finding supports surface cleaning as a necessary action that should be enforced and repeated becuase it may play a key role in halting SARS-CoV-2 transmission and mitigating the COVID-19 pandemic.

posted by katra at 7:06 PM on July 20, 2020

Not exactly answering your question, but most lay people seem to feel that cleaning and disinfecting are important (for example, lots of questions here focus on that kind of point) because handwashing and cleaning were emphasised a lot in the first few months of the pandemic. So even if there's now no strong basis for saying that it's particularly essential for covid-19, it probably does help people believe that the organisation is taking proper precautions and it will help prevent the spread of other illnesses like norovirus, so it's not without benefit generally.
posted by plonkee at 2:52 AM on July 21, 2020

What Do We Know About COVID-19 Transmission? (Young, Kelly D. MD, Emergency Medicine News: May 20, 2020 - Volume 42 - Issue 5B - doi: 10.1097/01.EEM.0000668064.35396.f0)

An epidemiologic investigation into the case of a woman in Charlotte, NC, who had left her house only once in three weeks to go to the pharmacy concluded that she was infected by touching the pharmacy keypad. (WCNC, Charlotte, NC, April 21, 2020; https://bit.ly/3d0MEO4.)

What’s the Risk of Catching Coronavirus From a Surface? (NYT, May 28, 2020, Updated Jul. 8, 2020 / Independent reprint)
Touching contaminated objects and then infecting ourselves with the germs is not typically how the virus spreads. But it can happen.

“What they’re saying is that high touch surfaces like railings and doorknobs, elevator buttons are not the primary driver of the infection in the United States,” said Erin Bromage, a comparative immunologist and biology professor at the University of Massachusetts, Dartmouth. “But it’s still a bad idea to touch your face. If someone who is infectious coughs on their hand and shakes your hand and you rub your eyes — yes, you’re infected. Someone’s drinking from a glass, and you pick it up near the rim and later rub your eyes or mouth, you’re infected.”

Also: Fact check: Sunlight does not kill the new coronavirus (USA Today, Mar. 30, 2020, Updated Apr. 5, 2020)
posted by katra at 12:20 PM on July 21, 2020

Our district sent a questionnaire to parents and asked what they thought about a wide variety of possible actions to help reduce spread, from hand sanitizing to surface cleaning to various super-duper filters in the air conditioning system and others dealing with improved ventilation.

So when the plan came out, there were pages and pages on hand sanitizing and cleaning surfaces, and zero on anything related to air circulation, air cleaning, air filtering, introducing more fresh air, limiting attendance or time spent via room size or fresh air availability, etc.

I was really surprised, because there were tons of things related to ventilation in the survey, and then zero of them made it to the final plan.

My guess is a confluence of two things:

#1. Parents came out massively in favor of hand washing and cleaning surfaces, because they understand that and not the other, more complex but effective stuff. Relatively few people understand the airborne virus thing, air circulation, fresh air, etc etc etc related to transmission of airborne virus.

#2. Really reliable guidance for schools is so lacking. (Two sources I've linked before, in addition to the CDC and American Academy of Pediatrics guidelines: JAMA, Science)

Also, following the CDC guidance would usually be a no-brainer. But as soon as it came out it was undermined at a very high level politically. So instead of a no-brainer basic essentials guide that every school district could safely follow, it became a sort of political third-rail that a significant contingent of parents and district staff see as a bad list of things to avoid.

And this, unfortunately, plays into reason #3:

#3. Decision-making structure for these plans. So Districts have a Committee, they meet, they are sorting through tons of conflicting advice.

Washing hands and cleaning surfaces are things that no one disagrees with. These proposals get to the District's Committee, no one objects--whoosh, it's approved. Hooray!! Something we all agree on!

And they are in fact helpful measures, though very, very modestly so. 1% improvement in conditions but 100% Committee agreement.

Then when we get to the measures that would make a much, much bigger difference in reducing transmission, they are also much, much more controversial. And also, just simply harder to understand and to discuss as a group. They take some real technical competence.

So you have an expensive solution that would make a huge difference in virus transmission, so a 50% reduction. But 33% of the Committee objects on political grounds because they don't think it will really work. And another 33% disagrees because of cost, and don't see the positive benefit/cost ratio because they don't understand the full benefit. The 10% of the Committee who actually understand the issue are just dying inside. But they don't have the Committee votes.

(Additionally, a few loud opponents in a Committee setting can often derail major initiatives, even if they don't really have a majority on their side.)

So 50% potential improvement in conditions but 66% committee controversy, thus it doesn't make it into the plan.

And so it goes for everything. The deciding factor for inclusion isn't actual effectiveness, but rather degree of agreement vs controversy vs understanding among committee members.

And we end up with the plan we have, which puts great emphasis on items of minimal effectiveness. Because everyone agrees they do help--a little.

We probably need a specific name for this particular dynamic, because it is very common. Perhaps there already is a name--for example, it is quite similar to bikeshedding.
posted by flug at 9:36 PM on July 21, 2020

did anyone post this article yet?

spoiler: it says that cleaning is theater and not relevant at all.
posted by fingersandtoes at 12:38 PM on July 28, 2020