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WHO Changes 'Social Distancing' to 'Physical Distancing'

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Re: WHO Changes 'Social Distancing' to 'Physical Distancing'

#41

Post by hanche »

zzzcpan wrote: post #37
robocat wrote: post #2

I am hoping we have good science behind the “1.5 metre” distance rule... Does anyone have links to videos that show how breath swirls around, especially in outdoor areas? I guess I could get some pollen and try and model it myself!

This is the only study I know on aerosol transmission of SARS-CoV-2: https://www.biorxiv.org/content/10.1101/2020.03.08.982637v1.... (it doesn't support such simplistic advice of 1.5 meters distance, that advice seems pretty bad and dangerous)

Perhaps simplistic advice is better than no advice.

The way I see it, the advice we're given is not so much geared towards safety of the individual as to slowing the spread of the infection, basically lowering R0. They could say five meters, but that is impractical, so would be universally ignored. So the idea would be to settle for a recommended distance that seems practical, while lowering the risk of infection to a reasonable degree.

Let's face it: Whether you or I get through this unharmed, is of little or no significance compared to what will happen on a larger scale.

Re: WHO Changes 'Social Distancing' to 'Physical Distancing'

#43

Post by shrikant »

humblebee wrote: post #30
wenc wrote: post #17

I wonder: who came up with the term "social distancing"? The wikipedia [1] article doesn't say. Was it widely used prior to this? [1] https://en.wikipedia.org/wiki/Social_distancing

My friends and I had the same question. I did a little searching and found an interesting paper[0]. The oldest reference it has is from 2009[1] [0] https://journals.plos.org/ploscompbiol/article?id=10.1371/jo... [1] Kelso J,Milne G,Kelly H (2009) Simulation suggests that rapid activation of social distancing can arrest epidemic development due to a novel strain of influenza. BMC Public Health 9: 117.

I found an earlier reference (May 2006) in the context of transmission prevention here [0]:

> The idea that within a week or two of a pandemic's initiation we could quench it by saturating a ring of at-risk population with oseltamivir, achieving 90% coverage and high compliance, and at the same time impose movement restrictions and social distancing—all this depending on the causal virus having an Ro [0] https://www.thelancet.com/journals/lancet/article/PIIS014067...

It's also referenced here [1] in the context of the SARS pandemic, but I'd argue that the usage isn't quite the same.

[1] https://www.liebertpub.com/doi/pdf/10.1089/bsp.2004.2.265

Re: WHO Changes 'Social Distancing' to 'Physical Distancing'

#44

Post by lawlessone »

nabla9 wrote: post #39
robocat wrote: post #2

I am hoping we have good science behind the “1.5 metre” distance rule... Does anyone have links to videos that show how breath swirls around, especially in outdoor areas? I guess I could get some pollen and try and model it myself!

Here: 1) Exposure to influenza virus aerosols during routine patient care. https://academic.oup.com/jid/article/207/7/1037/2192312 >HCPs within 1.829 m of patients with influenza could be exposed to infectious doses of influenza virus, primarily in small-particle aerosols. 2) Short-range airborne transmission of expiratory droplets between two people. https://www.ncbi.nlm.nih.gov/pubmed/27287598 >The threshold distan…

>The goal is to get as small dose viruses at once as possible. Immune system can usually fight off small exposure.

This is interesting, i had always thought it was binary, either you get infected or you don't

Re: WHO Changes 'Social Distancing' to 'Physical Distancing'

#45

Post by iamaelephant »

fenwick67 wrote: post #42

So what is the term for things like "don't go over to your friend's house for beers this Friday" or "don't throw a house party"? Just "stay in"? What about "don't take your whole family to the grocery store"?

Physical distancing.

Re: WHO Changes 'Social Distancing' to 'Physical Distancing'

#46

Post by fyp »

In china, a lot the spread isn't from stranger to stranger but family to family:

https://www.bloomberg.com/news/articles/2020-02-28/coronavir...

https://youtu.be/e3gCbkeARbY?t=37

How do you do physical distancing within your home? Eat meals alone? Don't share cups/plates? Wear gloves for doorknobs? I feel like there's currently no solution for this.

Re: WHO Changes 'Social Distancing' to 'Physical Distancing'

#47

Post by xxpor »

fyp wrote: post #46

In china, a lot the spread isn't from stranger to stranger but family to family: https://www.bloomberg.com/news/articles/2020-02-28/coronavir... https://youtu.be/e3gCbkeARbY?t=37 How do you do physical distancing within your home? Eat meals alone? Don't share cups/plates? Wear gloves for doorknobs? I feel like there's currently no solution for this.

You can't avoid a lot of that, given the physical constraints within a home. This just means it's even more critical for people who live with others to do physical distancing so they don't bring it home.

Re: WHO Changes 'Social Distancing' to 'Physical Distancing'

#49

Post by buboard »

fyp wrote: post #46

In china, a lot the spread isn't from stranger to stranger but family to family: https://www.bloomberg.com/news/articles/2020-02-28/coronavir... https://youtu.be/e3gCbkeARbY?t=37 How do you do physical distancing within your home? Eat meals alone? Don't share cups/plates? Wear gloves for doorknobs? I feel like there's currently no solution for this.

That may well be the reason why the virus spread continued in italy and Spain, from parents to grandparents.

Re: WHO Changes 'Social Distancing' to 'Physical Distancing'

#50

Post by throwanem »

lawlessone wrote: post #44
nabla9 wrote: post #39

Earlier quoted context omitted.

Here: 1) Exposure to influenza virus aerosols during routine patient care. https://academic.oup.com/jid/article/207/7/1037/2192312 >HCPs within 1.829 m of patients with influenza could be exposed to infectious doses of influenza virus, primarily in small-particle aerosols. 2) Short-range airborne transmission of expiratory droplets between two people. https://www.ncbi.nlm.nih.gov/pubmed/27287598 >The threshold distan…

>The goal is to get as small dose viruses at once as possible. Immune system can usually fight off small exposure. This is interesting, i had always thought it was binary, either you get infected or you don't

Nope. The higher the dose you get at any given time, the likelier it is that enough virions will establish footholds in enough cells to overwhelm the local protective response and survive to replicate.

To be clear, that's not an antibody-mediated immune response, which takes longer. Before then, cells penetrated by virus particles often undergo apoptosis, self-destructing to defend the larger organism by preventing the virus from hijacking the cell's machinery to reproduce itself. Sometimes the virus wins, though. So the more particles you're exposed to, the higher the odds that one or more will establish itself and start making you sick.

For more, see e.g. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2517702/ - but if you don't want that level of detail, you can just think of it as "flattening the curve" on an individual scale, and not really go far wrong.

edit: More accurate use of "immune" now that I'm not commenting from a phone with a small screen. Apoptosis isn't initiated by the immune system, but rather within the affected cell itself, and doesn't only occur in response to viral invasion; many types of cellular injury or damage can cause it, including most of the ways that a cell can become precancerous. (Which happens a lot more often than you might think! But most such cells self-destruct before they can give rise to a tumor.)

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