4 ms·

The point is, in Japan's case masks appear to be 100% effective, or very close to it, in eliminating transmission on public transport. Do you have a reason to

The point is, in Japan's case masks appear to be 100% effective, or very close to it, in eliminating transmission on public transport. Do you have a reason to believe greater prevalence of the virus is linked to lower mask effectiveness in this specific context?

gok 6y ago
Wearing masks being 100% effective is utterly impossible. The most positive studies show them being more like 85% effective. There simply are no infected people on Japan's transit, due to the country's intensive, early quarantining procedures. (same with Korea and Taiwan)
georgespencer 6y ago
> in Japan's case masks appear to be 100% effective I think important to note that no serious person could or would ever claim that masks are "100% effective". You're drawing this conclusion from the absence of outbreaks on a depleted Tokyo metro and (although you don't mention it) Paris too. It isn't possible to legislate for manufacturing defects in masks, suboptimal storage conditions, wearing it incorrectly, etc. That's before you even get to the myriad confounding variables which stem from different cultures AND weigh the fact that you're drawing your conclusion -- which will result in preventable deaths, if it's wrong -- from an absence of evidence to the contrary (!). The article you linked and many others on this topic highlight that Japan adopted a "three C's strategy" which has led to social distancing on the Metro in addition to masks (which were already a popular facet of commuting in Tokyo). So just like London, they're doing social distancing and wearing a mask. Worth observing that New York's mask-wearing MTA employees have been disproportionately blighted by COVID-related mortality[1], and London's bus drivers aren't faring (ha) much better[2]. > Do you have a reason to believe greater prevalence of the virus is linked to lower mask effectiveness in this specific context? I didn't suggest that the virus being more prevalent lowers the effectiveness of masks. I pointed out that prevalence is more than 600x higher in London than Japan. The Tokyo Metro transports around 7m passengers per day, which yields 35 infected passengers on the system each day (0.5 per capita). TFL moves 9 million passengers each day, with a 333 per capita instance of COVID-19 infection, which means nearly 30,000 infected individuals. If masks are 100% effective when worn properly, but 10% of the time are either defective or worn improperly, a peak journey in Tokyo would expose 700,000 people to risk from 3.5 COVID carriers. You could express this as a ratio of 200,000 at risk of contracting for every 1 person at risk of spreading the disease. In London the same math sees 900,000 people exposed to risk from 3,000 people. The ratio becomes 300:1. When you consider it in these terms it doesn't seem imprudent to reduce capacity AND insist on masks. At least until there are more meaningful data to support decision making. [1] https://www.thecity.nyc/2020/6/1/21277407/nyc-subway-crews-hit-hardest-by-coronavirus-pandemic-mta-numbers-show https://www.thecity.nyc/2020/6/1/21277407/nyc-subway-crews-h... [2] https://www.nytimes.com/2020/05/02/world/europe/coronavirus-london-buses.html https://www.nytimes.com/2020/05/02/world/europe/coronavirus-...
Noos 6y ago
Japan also has a 99% conviction rate in their criminal justice system. I wouldn't trust their statistics uncritically. It's often more a matter of what isn't being said.

gok 6y ago

Wearing masks being 100% effective is utterly impossible. The most positive studies show them being more like 85% effective. There simply are no infected people on Japan's transit, due to the country's intensive, early quarantining procedures. (same with Korea and Taiwan)

georgespencer 6y ago

> in Japan's case masks appear to be 100% effective I think important to note that no serious person could or would ever claim that masks are "100% effective". You're drawing this conclusion from the absence of outbreaks on a depleted Tokyo metro and (although you don't mention it) Paris too. It isn't possible to legislate for manufacturing defects in masks, suboptimal storage conditions, wearing it incorrectly, etc. That's before you even get to the myriad confounding variables which stem from different cultures AND weigh the fact that you're drawing your conclusion -- which will result in preventable deaths, if it's wrong -- from an absence of evidence to the contrary (!). The article you linked and many others on this topic highlight that Japan adopted a "three C's strategy" which has led to social distancing on the Metro in addition to masks (which were already a popular facet of commuting in Tokyo). So just like London, they're doing social distancing and wearing a mask. Worth observing that New York's mask-wearing MTA employees have been disproportionately blighted by COVID-related mortality[1], and London's bus drivers aren't faring (ha) much better[2]. > Do you have a reason to believe greater prevalence of the virus is linked to lower mask effectiveness in this specific context? I didn't suggest that the virus being more prevalent lowers the effectiveness of masks. I pointed out that prevalence is more than 600x higher in London than Japan. The Tokyo Metro transports around 7m passengers per day, which yields 35 infected passengers on the system each day (0.5 per capita). TFL moves 9 million passengers each day, with a 333 per capita instance of COVID-19 infection, which means nearly 30,000 infected individuals. If masks are 100% effective when worn properly, but 10% of the time are either defective or worn improperly, a peak journey in Tokyo would expose 700,000 people to risk from 3.5 COVID carriers. You could express this as a ratio of 200,000 at risk of contracting for every 1 person at risk of spreading the disease. In London the same math sees 900,000 people exposed to risk from 3,000 people. The ratio becomes 300:1. When you consider it in these terms it doesn't seem imprudent to reduce capacity AND insist on masks. At least until there are more meaningful data to support decision making. [1] https://www.thecity.nyc/2020/6/1/21277407/nyc-subway-crews-hit-hardest-by-coronavirus-pandemic-mta-numbers-show https://www.thecity.nyc/2020/6/1/21277407/nyc-subway-crews-h... [2] https://www.nytimes.com/2020/05/02/world/europe/coronavirus-london-buses.html https://www.nytimes.com/2020/05/02/world/europe/coronavirus-...

Noos 6y ago

Japan also has a 99% conviction rate in their criminal justice system. I wouldn't trust their statistics uncritically. It's often more a matter of what isn't being said.