[oldalum]

But it's also important to acknowledge that under any "activity" scenario, risk goes up, including fatality risk in some quantum, particularly for vulnerable groups.  Incremental risk, weighed against incremental benefit; and is that risk "acceptable" by whatever standards/thinking is in place.  

Yes I agree. Unfortunately risk is difficult to judge because our knowledge of virus transmission is still so uncertain and because risk depends on the risk-reduction activities of those infected and those subject to infection, as well as the effectiveness of testing and tracing. If everyone wore N95 or KN95 properly fitting masks whenever appropriate, I wonder if the risk of transmission would be reduced so much that most of the economy could re-open fully. I wear a well-fitting KN95 mask around (widely available for purchase, could be provided to everyone by the government) and, perhaps foolishly, feel pretty well protected in it. I wonder if teachers and students all wear them, would the risk of transmission be acceptably low and in-classroom learning could resume, at least at the higher levels?
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Addendum: from a news report yesterday, from South Korea:

Do masks really work? Ask the dozens of Starbucks customers who tested positive for COVID-19 in Seoul this month after a woman with coronavirus sat under one of the cafe’s air-conditioners.

According to a local news report, at least 56 coronavirus cases have been linked to that one customer. The kicker: The four masked workers avoided infection.

The Starbucks SBUX, -0.83% patrons, according to officials, weren’t consistently wearing masks because, of course, it’s hard to enjoy a latte when you can’t access your mouth.

“This speaks volumes about the role masks can play,” Ma Sang Hyuk, a pediatric infectious diseases physician in South Korea, explained to Bloomberg News. “Masks may not provide 100% protection, but there’s nothing out there that’s as effective.”

Local authorities made it mandatory this week for everybody to wear masks both indoors and outdoors, as the greater Seoul area has seen a surge in coronavirus cases.

[oldalum]

But it's also important to acknowledge that under any "activity" scenario, risk goes up, including fatality risk in some quantum, particularly for vulnerable groups.  Incremental risk, weighed against incremental benefit; and is that risk "acceptable" by whatever standards/thinking is in place.  

Yes I agree. Unfortunately risk is difficult to judge because our knowledge of virus transmission is still so uncertain and because risk depends on the risk-reduction activities of those infected and those subject to infection, as well as the effectiveness of testing and tracing. If everyone wore N95 or KN95 properly fitting masks whenever appropriate, I wonder if the risk of transmission would be reduced so much that most of the economy could re-open fully. I wear a well-fitting KN95 mask around (widely available for purchase, could be provided to everyone by the government) and, perhaps foolishly, feel pretty well protected in it. I wonder if teachers and students all wear them, would the risk of transmission be acceptably low and in-classroom learning could resume, at least at the higher levels?
___________________________________________________
Addendum: from a news report yesterday, from South Korea:

Do masks really work? Ask the dozens of Starbucks customers who tested positive for COVID-19 in Seoul this month after a woman with coronavirus sat under one of the cafe’s air-conditioners.

According to a local news report, at least 56 coronavirus cases have been linked to that one customer. The kicker: The four masked workers avoided infection.

The Starbucks SBUX, -0.83% patrons, according to officials, weren’t consistently wearing masks because, of course, it’s hard to enjoy a latte when you can’t access your mouth.

“This speaks volumes about the role masks can play,” Ma Sang Hyuk, a pediatric infectious diseases physician in South Korea, explained to Bloomberg News. “Masks may not provide 100% protection, but there’s nothing out there that’s as effective.”

Local authorities made it mandatory this week for everybody to wear masks both indoors and outdoors, as the greater Seoul area has seen a surge in coronavirus cases.