3 ms·

Wrong. It's much more nuanced than that. Surgical masks are not effective at preventing infection. They are effective at spreading infection. New data on asym

Wrong. It's much more nuanced than that. Surgical masks are not effective at preventing infection. They are effective at spreading infection. New data on asymptomatic spreaders means than public health authorities are considering changing their advice. The default assumption would then be that everyone has it, and should therefore wear a mask to prevent spreading it.

wetpaws 7y ago
>Surgical masks are not effective at preventing infection. They are effective at spreading infection. This is a common misconception, for which CDC is also partially the one to be blamed. Laboratory tests find that improvised cloth masks block 60 – 80% of virus particles Most experts in the early 2000s agreed that these masks were probably better than nothing. https://bmjopen.bmj.com/content/bmjopen/5/4/e006577.full.pdf https://bmjopen.bmj.com/content/bmjopen/5/4/e006577.full.pdf https://www.cambridge.org/core/services/aop-cambridge-core/content/view/0921A05A69A9419C862FA2F35F819D55/S1935789313000438a.pdf/testing_the_efficacy_of_homemade_masks_would_they_protect_in_an_influenza_pandemic.pdf https://www.cambridge.org/core/services/aop-cambridge-core/c... http://akkie.mods.jp/2019-nCoV/images/c/c0/%E3%82%B5%E3%83%BC%E3%82%B8%E3%82%AB%E3%83%AB%E3%83%9E%E3%82%B9%E3%82%AF%E5%8C%BB%E7%99%82vs%E5%B8%82%E4%B8%AD%E6%84%9F%E6%9F%93%E4%BA%88%E9%98%B2%EF%BC%9A%E7%B7%8F%E8%AA%AC_%282015%2C_MacIntyre%29.pdf http://akkie.mods.jp/2019-nCoV/images/c/c0/%E3%82%B5%E3%83%B...
- bregma 7y ago
  > Laboratory tests find that improvised cloth masks block 60 – 80% of virus particles How many virus particles do you need to become infected? Is 20% of the load in a typical aerosol droplet from an asymptomatic infected person above or below that critical number?
  - wetpaws 7y ago
    https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30232-2/fulltext https://www.thelancet.com/journals/laninf/article/PIIS1473-3... >higher viral loads associated with severe clinical outcomes
  - sudosysgen 7y ago
    It's a numbers game. There is a certain probability that each virion can spur and infection, so the less you get the better. If virions had a 100% infection chance then sure, but it's much lower than that.
Enginerrrd 7y ago
>Surgical masks are not effective at preventing infection. Actually, they very much are. 1. Regular old surgical masks (not N95 respirators), when worn by the public without training, had a strong protective effect for the people wearing them during the SARS-CoV-1 outbreak. They reduced the risk of infection by ~70%. (Source: https://wwwnc.cdc.gov/eid/article/10/2/03-0730_article https://wwwnc.cdc.gov/eid/article/10/2/03-0730_article) The CDC even coauthored this one. 2. Despite being very different in their ability to actually filter out fine particles, N95 respirators and surgical masks actually show no significant difference in their ability to prevent diagnosed respiratory infections including influenza, when worn by healthcare workers according to two large meta-studies. Though both had a protective effect over no mask. (Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4868605/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4868605/) (2nd source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5779801/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5779801/) 3. When infected people wear a mask, it does help reduce the amount of viral shedding which occurs, presumably making them less likely to infect others. (Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3591312/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3591312/) In fact, if you dig into the research evaluating different mask types including homemade masks, one of them suggests that the masks are actually MORE protective on the way in than they are in preventing shedding of aerosols: (Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2440799/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2440799/) (2nd source: https://www.researchgate.net/publication/258525804_Testing_the_Efficacy_of_Homemade_Masks_Would_They_Protect_in_an_Influenza_Pandemic https://www.researchgate.net/publication/258525804_Testing_t...)

wetpaws 7y ago

>Surgical masks are not effective at preventing infection. They are effective at spreading infection. This is a common misconception, for which CDC is also partially the one to be blamed. Laboratory tests find that improvised cloth masks block 60 – 80% of virus particles Most experts in the early 2000s agreed that these masks were probably better than nothing. https://bmjopen.bmj.com/content/bmjopen/5/4/e006577.full.pdf https://bmjopen.bmj.com/content/bmjopen/5/4/e006577.full.pdf https://www.cambridge.org/core/services/aop-cambridge-core/content/view/0921A05A69A9419C862FA2F35F819D55/S1935789313000438a.pdf/testing_the_efficacy_of_homemade_masks_would_they_protect_in_an_influenza_pandemic.pdf https://www.cambridge.org/core/services/aop-cambridge-core/c... http://akkie.mods.jp/2019-nCoV/images/c/c0/%E3%82%B5%E3%83%BC%E3%82%B8%E3%82%AB%E3%83%AB%E3%83%9E%E3%82%B9%E3%82%AF%E5%8C%BB%E7%99%82vs%E5%B8%82%E4%B8%AD%E6%84%9F%E6%9F%93%E4%BA%88%E9%98%B2%EF%BC%9A%E7%B7%8F%E8%AA%AC_%282015%2C_MacIntyre%29.pdf http://akkie.mods.jp/2019-nCoV/images/c/c0/%E3%82%B5%E3%83%B...

bregma 7y ago
> Laboratory tests find that improvised cloth masks block 60 – 80% of virus particles How many virus particles do you need to become infected? Is 20% of the load in a typical aerosol droplet from an asymptomatic infected person above or below that critical number?
- wetpaws 7y ago
  https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30232-2/fulltext https://www.thelancet.com/journals/laninf/article/PIIS1473-3... >higher viral loads associated with severe clinical outcomes
- sudosysgen 7y ago
  It's a numbers game. There is a certain probability that each virion can spur and infection, so the less you get the better. If virions had a 100% infection chance then sure, but it's much lower than that.

Enginerrrd 7y ago

>Surgical masks are not effective at preventing infection. Actually, they very much are. 1. Regular old surgical masks (not N95 respirators), when worn by the public without training, had a strong protective effect for the people wearing them during the SARS-CoV-1 outbreak. They reduced the risk of infection by ~70%. (Source: https://wwwnc.cdc.gov/eid/article/10/2/03-0730_article https://wwwnc.cdc.gov/eid/article/10/2/03-0730_article) The CDC even coauthored this one. 2. Despite being very different in their ability to actually filter out fine particles, N95 respirators and surgical masks actually show no significant difference in their ability to prevent diagnosed respiratory infections including influenza, when worn by healthcare workers according to two large meta-studies. Though both had a protective effect over no mask. (Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4868605/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4868605/) (2nd source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5779801/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5779801/) 3. When infected people wear a mask, it does help reduce the amount of viral shedding which occurs, presumably making them less likely to infect others. (Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3591312/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3591312/) In fact, if you dig into the research evaluating different mask types including homemade masks, one of them suggests that the masks are actually MORE protective on the way in than they are in preventing shedding of aerosols: (Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2440799/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2440799/) (2nd source: https://www.researchgate.net/publication/258525804_Testing_the_Efficacy_of_Homemade_Masks_Would_They_Protect_in_an_Influenza_Pandemic https://www.researchgate.net/publication/258525804_Testing_t...)