[Deleted the CDC quote that COVID-19 is mainly spread “between people who are in close contact with one another (within about 6 feet)”, per Zvi’s criticism of the meme.]
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2B. If you do need to be around people, face away from them, minimize talking, etc.
According to the binary model established in the 1930s, droplets typically are classified as either (1) large globules of the Flüggian variety—arcing through the air like a tennis ball until gravity brings them down to Earth; or (2) smaller particles, less than five to 10 micrometers in diameter (roughly a 10th the width of a human hair), which drift lazily through the air as fine aerosols.
[...] Despite the passage of four months since the first known human cases of COVID-19, our public-health officials remain committed to policies that reflect no clear understanding as to whether it is one-off ballistic droplet payloads or clouds of fine aerosols that pose the greatest risk—or even how these two modes compare to the possibility of indirect infection through contaminated surfaces (known as “fomites”).
Gaining such an understanding is absolutely critical to the task of tailoring emerging public-health measures and workplace policies, because the process of policy optimization depends entirely on which mechanism (if any) is dominant:
1. If large droplets are found to be a dominant mode of transmission, then the expanded use of masks and social distancing is critical, because the threat will be understood as emerging from the ballistic droplet flight connected to sneezing, coughing, and laboured breathing. We would also be urged to speak softly, avoid “coughing, blowing and sneezing,” or exhibiting any kind of agitated respiratory state in public, and angle their mouths downward when speaking.
2. If lingering clouds of tiny aerosol droplets are found to be a dominant mode of transmission, on the other hand, then the focus on sneeze ballistics and the precise geometric delineation of social distancing protocols become somewhat less important—since particles that remain indefinitely suspended in an airborne state can travel over large distances through the normal processes of natural convection and gas diffusion. In this case, we would need to prioritize the use of outdoor spaces (where aerosols are more quickly swept away) and improve the ventilation of indoor spaces.
3. If contaminated surfaces are found to be a dominant mode of transmission, then we would need to continue, and even expand, our current practice of fastidiously washing hands following contact with store-bought items and other outside surfaces; as well as wiping down delivered items with bleach solution or other disinfectants.
Identified Super Spreader Events are Primarily Large Droplet Transmission
The article makes a strong case that in identified super spreader events [SSEs] the primary mode of transmission is large droplets. And that large droplets are spread in close proximity, by people talking (basically everything) or singing (several choir/singing practices) frequently or loudly, or laughing (many parties) and crying (funerals), or otherwise exhaling rapidly (e.g. the curling match) and so on.
There is a highly noticeable absence of SSEs that would suggest other transmission mechanisms. Subways and other public transit aren’t present, airplanes mostly aren’t present. Performances and showings of all kinds also aren’t present. Quiet work spaces aren’t present, loud ones (where you have to yell in people’s faces) do show up. University SSEs are not linked to classes (where essentially only the professor talks, mostly) but rather to socializing. [...]
Zvi argues that surfaces and small aerosolized droplets are unlikely to be major infection vectors for COVID-19. He discusses methods for avoiding large droplet transmission:
Large Droplets: Six Foot Rule is Understandable, But Also Obvious Nonsense
For large droplets, there is essentially zero messaging about angling downwards or avoiding physical actions that would expel more droplets, or avoiding being in the direct path of other people’s potential droplets.
Instead, we have been told to keep a distance of six feet from other people. We’ve told them that six feet apart is safe, and five feet apart is unsafe. Because the virus can only travel six feet.
That’s obvious nonsense. It is very clear that droplets can go much farther than six feet. Even more than that, the concept of a boolean risk function [i.e., one that sharply divides everything into either “risky” or “risk-free”, with no shades of grey] is insane. People expel virus at different velocities, from different heights, under different wind conditions and so on. The physics of each situation will differ. The closer you are, the more risk.
Intuitively it makes sense to think about something like an inverse square law until proven otherwise, so six feet away is about 3% of the risk of one foot away. That’s definitely not right, but it’s the guess I feel comfortable operating with.
Alas, that’s not the message. The message is 72 inches safe, 71 inches unsafe.
Unlike the previous case of obvious nonsense, there is a reasonable justification for this one. I am sympathetic. You get about five words. “Always stay six feet apart” is a pretty good five words. There might not be a better one. Six feet is a distance that you can plausibly mandate and still allow conversations and lines that are moderately sane, so it’s a reasonable compromise.
It’s a lie. It’s not real. As a pragmatic choice, it’s not bad.
The problem is it is being treated as literally real.
Joe Biden and Bernie Sanders met on a debate stage. The diagram plans had them exactly six feet apart.
In an article, someone invites the author, a reporter, to their house to chat. Says he’s prepared two chairs, six feet apart. “I measured them myself,” he says. [...]
And so on. People really are trying to make the distance exactly six feet as often as possible.
[...] This is society sacrificing bandwidth to get a message across. Again, I get it. The problem is we are also sacrificing any ability to convey nuance. We are incapable, after making this sacrifice, of telling people there is a physical world they might want to think about how to optimize. There is only a rule from on high, The Rule of Six Feet.
Thus, we may never be able to get people to talk softly into the ground rather than directly looking at each other and loudly and forcefully to ‘make up for’ the exact six foot distance, which happens to be the worst possible orientation that isn’t closer than six feet.
In theory, we can go beyond this. You get infected because droplets from an infected person travel out of their face and touch your face.
Thus, a line is remarkably safe if everyone faces the same way, modulo any strong winds. The person behind you has no vector to get to your face. And we can extend that. We can have one sidewalk where people walk north, and another on the other side of the street where people walk south. If you see someone approaching from the other direction, turn around and walk backwards while they ensure the two of you don’t collide. If necessary, stand in place for that reason. Either way, it should help – if this is the mechanism we are worried about.
[...] Yes, it’s annoying to not face other people, but you absolutely can have a conversation while facing away from each other. It’s a small price to pay.
In similar fashion, it seems a small price to pay to shut the hell up whenever possible, while out in public. Talking at all, when around those outside your household, can be considered harmful and kept to a bare minimum outright (and also it should be done while facing no one).
Zvi emphasizes that there’s much more benefit to slightly reducing the risk from the largest infection sources (including large droplets as a category), than from hugely reducing the risk from fairly unlikely infection sources:
Focus Only On What Matters
[...] Within those big risks, small changes matter. They matter more than avoiding small risks entirely.
A single social event, like a funeral, birthday party or wedding, might well by default give any given person a 30%+ rate to infect any given other person at that event if the event is small, and a reasonably big one even if large. You only need one. Keeping slightly more distance, speaking slightly less loudly, and so on, at one such event, is a big risk reduction. [...]
Whereas a ‘close contact’ that doesn’t involve talking or close interaction probably gives more like (spitballing a guess, but based on various things) an 0.03% rate of infection if the other person is positive, and likely with a lower resulting viral load. Certainly those contacts add up, but not that fast. Thus, a subway car full of “close contact” might give you 10 of them per day, most of whom are not, at any given time, infectious. If this model is correct.
[...] Slight reductions in the frequency and severity of your very risky actions is much more important than reducing the frequency of nominally risky actions.
The few times you end up talking directly with someone in the course of business, the one social gathering you attend, the one overly crowded store you had to walk through, will dominate your risk profile. Be paranoid about that, and think how to make it less risky, or ideally avoid it. Don’t sweat the small stuff.
And think about the physical world and what’s actually happening around you!
And:
My best guess is there is something like 5-10 times as much risk indoors versus the same activity outdoors. [...]
The combination of quick and outdoors and not-in-your-face probably effectively adds up to safe, especially if you add in masks. During the peak epidemic in New York things were so intense that it would have been reasonable to worry about miasma. Now, I would do my best to keep my distance and avoid talking at each other, but mostly not worry about incidental interactions.
I do expect there to be a spike in cases as the result of protests and civil unrest.. To not see one would be surprising, and would update me in favor of outdoor activities being almost entirely harmless.
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2C. If you do need to be around people, wear something over your mouth and nose.
[Deleted the advice for individuals not to buy medical-grade masks because it doesn’t currently seem like good advice (and I’m not particularly convinced it was ever good advice).]
Zvi Mowshowitz writes, “[E]ven cloth masks on both ends of an interaction are almost certainly good for a 25% reduction in risk and probably 50%-75%.”
It’s been months. We don’t have concrete examples of infection via surfaces. At all. It increasingly seems like while such a route is possible, and must occasionally happen, getting enough virus to cause an infection, in a live state, via this route, is very hard. When you wash your hands and don’t touch your face, it’s even harder than that.
Meanwhile, those who refuse to touch surfaces like a pizza delivery box end up in more crowded locations like grocery stores, resulting in orders of magnitude more overall risk.
[...] Until I get very unexpected evidence, surfaces are mostly not a thing anymore. If lots of people touch stuff and then you touch it, sure, wash your hands after and be extra careful to not touch your face in the interim. Otherwise, stop worrying about it.
[… Food] is at most minimally risky, even if it doesn’t get heated enough to reliably and fully kill the virus. You don’t have to ruin all your food. People are often avoiding foods that seem risky. Once again, it makes sense that it could be risky, but in practice it’s been months and it does not seem to work that way. The precautions people are taking will incidentally be more than good enough to guard against contamination of food at sufficient levels to be worth worrying about. I mean, sure, don’t eat at a buffet, but it’s not like any of them are going to be open, and even then the (also mostly safe) surfaces are likely scarier than the food.
[...] Your risk is from the waiter, or from the other diners, being in that room with you for a while. Thus, takeout, delivery and/or eating outdoors.
I agree with Zvi that it seems increasingly likely that surface transmission is rare, though he seems to be wrong that there are no examples (see comments), and I haven’t seen a clear argument for whether the number of COVID-19 cases caused by surface transmission is closer to 1⁄10 of all cases versus, say, 1⁄10,000. Given my own circumstances, I’m likely to do things like “order delivery pizza” more often in the weeks to come, but I’ll also likely make use of Yao Lu’s tips while infections are still commonplace in my part of the US:
I’m a chemo nurse, this is what I tell my high-risk patients:
I personally don’t trust takeout that much because I think a lot of restaurant workers don’t have sick leave, so it’s more likely your food was prepared by someone symptomatic. But you can cut the risk to near zero by doing this:
1. Wash your hands well
2. Put your own bowl on your kitchen counter
3. Pick up the restaurant container, and pour the food into your own bowl
4. Throw away the restaurant container
5. Wash your hands well
6. Thoroughly heat up the food. (at least 70C for a minute, or whatever the best current guideline says)
If you do this, in this order, you are extremely safe even if someone coughed viruses all over the food and the container. Heat would kill the virus, and handwashing would prevent indirect transmission from the bag/container.
[Deleted this section because the post is getting long and this seems messy and uncertain. I’ll reproduce the Apr. 26 version of the section in a reply to this comment for when I want to link directly to it.]
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2J. Run an air filter.
[Provisionally deleted “Also, quit smoking.” because I haven’t been keeping up with the debate about cigarettes or nicotine.]
___
3A. Prepare in advance.
Plan in advance what hospital you’ll go to if necessary, and be ready to call a doctor if you have troubling symptoms. Zvi Mowshowitz writes:
Medical care matters [for fatality rates]. Total breakdown of medical care in practice leads to several times the fatality rate under regular circumstances. High quality treatment at current knowledge levels can probably drive death rates down further, so the ratio between full success and complete breakdown can be rather large – something like an order-of-magnitude difference between 0.2% and 2%.
I don’t have a strong opinion at this point about particular medical treatments beyond the above.
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3G. Monitor for clotting problems.
Jim Babcock said on Apr. 28,
My first-pass literature review turned up some claimed mechanisms by which platelets and clotting may serve an immune purpose. I don’t know if that’s what happening here, but there’s a possibility that this works like fever reduction: helpful in extreme cases, bad in minor cases and early in the progression.
Low-dose heparin seems to be common hospital protocol now, so data should be forthcoming for that scenario. I don’t know what recommendation to give to minor cases self-treating at home, though.
[I meant to add the above before, but forgot about it. This is part of why I withdrew the recommendation that people take aspirin at home whenever they start showing COVID-19 symptoms.]
[Copy of the Apr. 26 section “Maybe stop taking ibuprofen/advil?”, deleted from the main text Jun. 2. A still earlier version just said that some sources were warning about NSAIDs and to therefore avoid them out of an abundance of caution.]
Human pathogenic coronaviruses (severe acute respiratory syndrome coronavirus [SARS-CoV] and SARSCoV-2) bind to their target cells through angiotensin-converting enzyme 2 (ACE2), which is expressed by epithelial cells of the lung, intestine, kidney, and blood vessels.[4] The expression of ACE2 is substantially increased in patients with type 1 or type 2 diabetes, who are treated with ACE inhibitors and angiotensin II type-I receptor blockers (ARBs).[4] Hypertension is also treated with ACE inhibitors and ARBs, which results in an upregulation of ACE2.[5] ACE2 can also be increased by thiazolidinediones and ibuprofen. These data suggest that ACE2 expression is increased in diabetes and treatment with ACE inhibitors and ARBs increases ACE2 expression. Consequently, the increased expression of ACE2 would facilitate infection with COVID-19. We therefore hypothesise that diabetes and hypertension treatment with ACE2-stimulating drugs increases the risk of developing severe and fatal COVID-19.
Qiao et al. conclude that ibuprofen enhances ACE2 in diabetic rats. Qiao et al. is the only study I’ve seen on ‘ibuprofen increases ACE2’, and this claim is uncited in Fang et al. The ibuprofen-ACE2-COVID link doesn’t seem to be widely known / accepted / cared about, based on the discussion on Science Translational Medicine (which argues increased ACE2 might reduce COVID-19 severity; see also the comment section) and Snopes. I also don’t know whether I should expect other NSAIDs to interact with ACE2 in the same way as ibuprofen.
On Mar. 14, Samira Jeimy wrote: “In Germany and France, ICU physicians have noticed that the common thread amongst young patients needing #COVIDー19 related ICU admission is that they had been using NSAIDS (Advil, Motrin, Aleve, Aspirin).” She cites the Lancet paper and Day:
Scientists and senior doctors have backed claims by France’s health minister that people showing symptoms of covid-19 should use paracetamol (acetaminophen) rather than ibuprofen, a drug they said might exacerbate the condition.
The minister, Oliver Veran, tweeted on Saturday 14 March that people with suspected covid-19 should avoid anti-inflammatory drugs. “Taking anti-inflammatory drugs (ibuprofen, cortisone . . .) could be an aggravating factor for the infection. If you have a fever, take paracetamol,” he said.
His comments seem to have stemmed in part from remarks attributed to an infectious diseases doctor in south west France. She was reported to have cited four cases of young patients with covid-19 and no underlying health problems who went on to develop serious symptoms after using non-steroidal anti-inflammatory drugs (NSAIDs) in the early stage of their symptoms. The hospital posted a comment saying that public discussion of individual cases was inappropriate.
But Jean-Louis Montastruc, a professor of medical and clinical pharmacology at the Central University Hospital in Toulouse, said that such deleterious effects from NSAIDS would not be a surprise given that since 2019, on the advice of the National Agency for the Safety of Medicines and Health Products, French health workers have been told not to treat fever or infections with ibuprofen.
Experts in the UK backed this sentiment. Paul Little, a professor of primary care research at the University of Southampton, said that there was good evidence “that prolonged illness or the complications of respiratory infections may be more common when NSAIDs are used—both respiratory or septic complications and cardiovascular complications.”
He added, “The finding in two randomised trials that advice to use ibuprofen results in more severe illness or complications helps confirm that the association seen in observational studies is indeed likely to be causal. Advice to use paracetamol is also less likely to result in complications.”
Ian Jones, a professor of virology at the University of Reading, said that ibuprofen’s anti-inflammatory properties could “dampen down” the immune system, which could slow the recovery process. He added that it was likely, based on similarities between the new virus (SARS-CoV-2) and SARS I, that covid-19 reduces a key enzyme that part regulates the water and salt concentration in the blood and could contribute to the pneumonia seen in extreme cases. “Ibuprofen aggravates this, while paracetamol does not,” he said.
Charlotte Warren-Gash, associate professor of epidemiology at the London School of Hygiene and Tropical Medicine, said: “For covid-19, research is needed into the effects of specific NSAIDs among people with different underlying health conditions. In the meantime, for treating symptoms such as fever and sore throat, it seems sensible to stick to paracetamol as first choice.” [...]
In the UK, paracetamol would generally be preferred over non-steroidal anti-inflammatory drugs (“NSAIDS”) such as ibuprofen to relieve symptoms caused by infection such as fever. This is because, when taken according to the manufacturer’s and/or a health professional’s instructions in terms of timing and maximum dosage, it is less likely to cause side effects. Side effects associated with NSAIDs such as ibuprofen, especially if taken regularly for a prolonged period, are stomach irritation and stress on the kidneys, which can be more severe in people who already have stomach or kidney issues. It is not clear from the French Minister’s comments whether the advice given is generic ‘good practice’ guidance or specifically related to data emerging from cases of Covid-19 but this might become clear in due course.
So most sources seem to agree that acetaminophen is at least a bit better than ibuprofen for treating fever-causing illnesses in general; but there’s confusion and disagreement about whether ibuprofen is unusually good or bad for COVID-19 in particular, and I don’t get the sense using ibuprofen is widely seen as a terrible idea. Elizabeth van Nostrand writes, “France is recommending against NSAIDs and against ibuprofen in particular. I will be very surprised if that ends up being born out (and WHO agrees with me)”.
Overall, the evidence is such that I’m avoiding ibuprofen right now, but I wouldn’t recommend going to huge lengths to avoid ibuprofen.
See 3E below on whether and when it’s a good idea to manually reduce fevers at all.
Updates, June 2:
___
2A. Avoid people, especially indoors.
[Section renamed from “Avoid people.”]
[Deleted the CDC quote that COVID-19 is mainly spread “between people who are in close contact with one another (within about 6 feet)”, per Zvi’s criticism of the meme.]
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2B. If you do need to be around people, face away from them, minimize talking, etc.
[New section.]
Jonathan Kay writes on Apr. 23,
Zvi Mowshowitz comments:
Zvi argues that surfaces and small aerosolized droplets are unlikely to be major infection vectors for COVID-19. He discusses methods for avoiding large droplet transmission:
Zvi emphasizes that there’s much more benefit to slightly reducing the risk from the largest infection sources (including large droplets as a category), than from hugely reducing the risk from fairly unlikely infection sources:
In another post, Zvi writes:
And:
___
2C. If you do need to be around people, wear something over your mouth and nose.
[Deleted the advice for individuals not to buy medical-grade masks because it doesn’t currently seem like good advice (and I’m not particularly convinced it was ever good advice).]
Zvi Mowshowitz writes, “[E]ven cloth masks on both ends of an interaction are almost certainly good for a 25% reduction in risk and probably 50%-75%.”
___
2D. Don’t put coronavirus in your face.
Zvi Mowshowitz argues:
I agree with Zvi that it seems increasingly likely that surface transmission is rare, though he seems to be wrong that there are no examples (see comments), and I haven’t seen a clear argument for whether the number of COVID-19 cases caused by surface transmission is closer to 1⁄10 of all cases versus, say, 1⁄10,000. Given my own circumstances, I’m likely to do things like “order delivery pizza” more often in the weeks to come, but I’ll also likely make use of Yao Lu’s tips while infections are still commonplace in my part of the US:
___
2G. Disinfect surfaces.
See also Zvi Mowshowitz’s recommendations to worry less about surfaces, quoted above.
___
2H. Maybe stop taking ibuprofen/advil?[Deleted this section because the post is getting long and this seems messy and uncertain. I’ll reproduce the Apr. 26 version of the section in a reply to this comment for when I want to link directly to it.]
___
2J. Run an air filter.
[Provisionally deleted “Also, quit smoking.” because I haven’t been keeping up with the debate about cigarettes or nicotine.]
___
3A. Prepare in advance.
Plan in advance what hospital you’ll go to if necessary, and be ready to call a doctor if you have troubling symptoms. Zvi Mowshowitz writes:
___
3G. Monitor for clotting problems.
Jim Babcock said on Apr. 28,
[I meant to add the above before, but forgot about it. This is part of why I withdrew the recommendation that people take aspirin at home whenever they start showing COVID-19 symptoms.]
[Copy of the Apr. 26 section “Maybe stop taking ibuprofen/advil?”, deleted from the main text Jun. 2. A still earlier version just said that some sources were warning about NSAIDs and to therefore avoid them out of an abundance of caution.]
Fang et al. write in The Lancet:
Qiao et al. conclude that ibuprofen enhances ACE2 in diabetic rats. Qiao et al. is the only study I’ve seen on ‘ibuprofen increases ACE2’, and this claim is uncited in Fang et al. The ibuprofen-ACE2-COVID link doesn’t seem to be widely known / accepted / cared about, based on the discussion on Science Translational Medicine (which argues increased ACE2 might reduce COVID-19 severity; see also the comment section) and Snopes. I also don’t know whether I should expect other NSAIDs to interact with ACE2 in the same way as ibuprofen.
On Mar. 14, Samira Jeimy wrote: “In Germany and France, ICU physicians have noticed that the common thread amongst young patients needing #COVIDー19 related ICU admission is that they had been using NSAIDS (Advil, Motrin, Aleve, Aspirin).” She cites the Lancet paper and Day:
The Snopes page above cites Tom Wingfield saying:
So most sources seem to agree that acetaminophen is at least a bit better than ibuprofen for treating fever-causing illnesses in general; but there’s confusion and disagreement about whether ibuprofen is unusually good or bad for COVID-19 in particular, and I don’t get the sense using ibuprofen is widely seen as a terrible idea. Elizabeth van Nostrand writes, “France is recommending against NSAIDs and against ibuprofen in particular. I will be very surprised if that ends up being born out (and WHO agrees with me)”.
Overall, the evidence is such that I’m avoiding ibuprofen right now, but I wouldn’t recommend going to huge lengths to avoid ibuprofen.
See 3E below on whether and when it’s a good idea to manually reduce fevers at all.