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How many microbes does it take to make you sick?

quantamagazine.org

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Re: How many microbes does it take to make you sick?

#41

Post by PaulKeeble »

gregwebs wrote: post #33

Great to see statistical thinking. There have been a lot of Covid shouting matches because people are trying to reduce things to binary. Masks don’t work! Actually, they work as advertised- only 95% effective at best (and a cloth mask may be 30%), not a binary protected or not. That’s effective at blocking particles. You are still guaranteed to get some virus particles. They are going to be in your respiratory tract…

Actually N95 is AT LEAST 95% effective. 95% is its worst case performance on a PM2.5 sized particle, at all other particle sizes it is better than 95% usually considerably. We also have N99 masks and even P100 respirators which do an even better job. We just need to start using them. We also need to educate ourselves how to fit and fit test a mask because if its leaking its not giving you that level of protection.

Re: How many microbes does it take to make you sick?

#42

Post by AnthonBerg »

sfblah wrote: post #16
Sakos wrote: post #5

Earlier quoted context omitted.

This is one of the reasons why masks are so important and why they don't need to be 100% effective. Just reducing the amount of viral load could turn a serious infection into something you might barely notice. edit: Imagine this being controversial. I didn't realize there were Covid deniers and skeptics here, because what I've stated is completely within established science.

What you said isn’t controversial. It’s definitely right. The issue with masks is one side started treating them like a talisman that makes infection impossible, which provoked the other side to say they do nothing. On a population level, masks are probably close to ineffective against a viral pathogen. You can read the relevant Cochrane review to see that. On an individual level they obviously do something, but you…

The un-cited Cochrane review in question does not say that.

From Cochrane.org:

Statement on 'Physical interventions to interrupt or reduce ... - Cochrane

Mar 10, 2023

Many commentators have claimed that a recently-updated Cochrane Review shows that 'masks don't work', which is an inaccurate and misleading interpretation. It would be accurate to say that the review examined whether interventions to promote mask wearing help to slow the spread of respiratory viruses, and that the results were inconclusive.

Repeating the important part:

the review examined whether interventions to promote mask wearing help to slow the spread of respiratory viruses

Conversely, here’s a good study that shows that consistent use of FFP3 respirator masks drastically reduced transmission among workers on a hospital ward: https://elifesciences.org/articles/71131

Note that the study only had the workers wearing FFP3 masks on shifts, and community transmission was high at the time. Therefore the study “leaked” and good masks work better than the numbers in the study might seem to indicate. Face-fitting masks do work, and very well. Of course they do. It’s all very clear if you dig into the aerosol physics.

Re: How many microbes does it take to make you sick?

#43

Post by AnthonBerg »

rootusrootus wrote: post #32
sfblah wrote: post #16

Earlier quoted context omitted.

What you said isn’t controversial. It’s definitely right. The issue with masks is one side started treating them like a talisman that makes infection impossible, which provoked the other side to say they do nothing. On a population level, masks are probably close to ineffective against a viral pathogen. You can read the relevant Cochrane review to see that. On an individual level they obviously do something, but you…

> For a surgical mask it was essentially nil. Is the surgeon wearing a mask to protect himself from me, or to protect me from him?

The surgeon is wearing it because of an old, old misinterpretation of reality.

This article is factually accurate: https://www.wired.com/story/the-teeny-tiny-scientific-screwu...

Re: How many microbes does it take to make you sick?

#44

Post by dorfsmay »

vikramkr wrote: post #14
dorfsmay wrote: post #8

Earlier quoted context omitted.

> boosting ourantibody response What I wonder is if we can develop immunity (not boosting, assuming never been infected before) from being exposed to small doses, or do we need at least one full blown infection.

Yep that's called vaccination! No need to get a full blown infection it's how we eradicated smallpox

Vaccination is using deactivated viruses. My question is can we get the same effect from exposure to small doses of live viruses.

The articles says exposure to tiny amount can "boost" immunity, which I assume means an immunity acquired earlier from a full blown infection (or vaccination).

Re: How many microbes does it take to make you sick?

#45

Post by hamburglar »

PaulKeeble wrote: post #41
gregwebs wrote: post #33

Great to see statistical thinking. There have been a lot of Covid shouting matches because people are trying to reduce things to binary. Masks don’t work! Actually, they work as advertised- only 95% effective at best (and a cloth mask may be 30%), not a binary protected or not. That’s effective at blocking particles. You are still guaranteed to get some virus particles. They are going to be in your respiratory tract…

Actually N95 is AT LEAST 95% effective. 95% is its worst case performance on a PM2.5 sized particle, at all other particle sizes it is better than 95% usually considerably. We also have N99 masks and even P100 respirators which do an even better job. We just need to start using them. We also need to educate ourselves how to fit and fit test a mask because if its leaking its not giving you that level of protection.

Well, the actual mask's performance is 95% effective, but you can't really make a guarantee about the overall worst case effectiveness when deployed by humans. N95 masks are not 95% effective on someone who has a big fluffy beard preventing a proper seal, for example. Or with people who use their gut feeling to decide where and when to put them on (like deciding if there's nobody in the elevator, you don't need it, ignoring the fact that someone may have gotten out of the elevator 20 seconds ago and left particulates in the air).

Re: How many microbes does it take to make you sick?

#46

Post by blurbleblurble »

gregwebs wrote: post #33

Great to see statistical thinking. There have been a lot of Covid shouting matches because people are trying to reduce things to binary. Masks don’t work! Actually, they work as advertised- only 95% effective at best (and a cloth mask may be 30%), not a binary protected or not. That’s effective at blocking particles. You are still guaranteed to get some virus particles. They are going to be in your respiratory tract…

I don't know if I'd call this "statistical thinking", at least not in the conventional sense of linear statistics with simple parametric models. If anything I'd call this "systems thinking", which unfortunately is not the kind of thinking I typically associate with "statistical thinking".

Re: How many microbes does it take to make you sick?

#47

Post by malfist »

dorfsmay wrote: post #44
vikramkr wrote: post #14

Earlier quoted context omitted.

Yep that's called vaccination! No need to get a full blown infection it's how we eradicated smallpox

Vaccination is using deactivated viruses. My question is can we get the same effect from exposure to small doses of live viruses. The articles says exposure to tiny amount can "boost" immunity, which I assume means an immunity acquired earlier from a full blown infection (or vaccination).

Vaccination can use deactivated viruses, but not always.

Re: How many microbes does it take to make you sick?

#48

Post by amanaplanacanal »

mozman wrote: post #39
Sakos wrote: post #5

Earlier quoted context omitted.

This is one of the reasons why masks are so important and why they don't need to be 100% effective. Just reducing the amount of viral load could turn a serious infection into something you might barely notice. edit: Imagine this being controversial. I didn't realize there were Covid deniers and skeptics here, because what I've stated is completely within established science.

There shouldn’t be any requirements for masks. Want to wear one? Great. Should I have to? No.

Is fairly common that, if you as an individual are doing something that poses a risk to other people, society will step in to attempt to change your behavior. You can argue that it is “wrong” for society to do that, of course.

Re: How many microbes does it take to make you sick?

#49

Post by maxerickson »

dorfsmay wrote: post #44
vikramkr wrote: post #14

Earlier quoted context omitted.

Yep that's called vaccination! No need to get a full blown infection it's how we eradicated smallpox

Vaccination is using deactivated viruses. My question is can we get the same effect from exposure to small doses of live viruses. The articles says exposure to tiny amount can "boost" immunity, which I assume means an immunity acquired earlier from a full blown infection (or vaccination).

Vaccines are rooted in a history of doing exactly what you are talking about. Smallpox variolation was done for hundreds of years before the development of the first vaccine.

https://www.cdc.gov/smallpox/history/history.html

Re: How many microbes does it take to make you sick?

#50

Post by amanaplanacanal »

PaulKeeble wrote: post #40

Last paragraphs are really important recommendations for how to end the pandemic. "Masking, increased ventilation and distancing reduces the number of microbes you’re exposed to. Vaccination increases the infectious dose. " We really need to move beyond vaccine only, its not working Covid is just too transmissible.

Ventilation changes seem like a big deal. Unfortunately that requires businesses and government to spend money, instead of putting the burden on individuals. This would require regulatory action, and at least in the US we have important culture wars to fight instead.
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