Masks provide extreme risk reduction for others if the wearer has the virus. Combine that with the 2-week incubation period and masks are quite effective.
Mask wearing was a law in SF during the 1918 epidemic and saved many lives. Once again, history is forgotten.
the risk reduction is actually very high. But the probability of being in the presence of the virus is very low. Health care workers treating infected patients have a 100% chance of being exposed so epidemiological risk reduction is large.
I think the "useless" part actually refers to the the fact that the public at large wont be wearing masks so a few people wearing masks might protect themselves, but does nothing to alleviate the overall spread of the virus.
The probability for being in the presence of the virus is very low right now in USA, but it's quite high in many other places (e.g. Iran) right now and in USA in the near future.
If media can be pushed to destigmatize wearing of masks and stigmatize not wearing of masks, then this (combined with starting manufacturing large quantities of masks) would alleviate the overall spread of the virus in the post-containment mitigation phase, in which many countries are right now.
I understand that wearing a mask doesn't prevent the wearer (for most common masks) but instead protects other people. Should you be a carrier. It slows the spread, which is a good thing?
What is your basis for this? My understanding is that an N95 mask, worn by following the directions on the box, provides significant protection to the wearer. Also, if it has a vent for exhaling, that would suggest it is not necessarily such good protection for others.
In matters of life and death, being careful is important. Taleb and others have a lot to say about tail risk, and coronavirus looks like a large tail risk to me. If I were a resident or planned an urgent visit in a Seattle nursing home I'd spend a good bit of money on PPE.
The lottery ticket analogy does not work well. I'm reminded instead of the scenes in the Chernobyl mini-series where individuals are sent into unknown dangers- dangers that are impossible to see, difficult to understand, and require conscious thought and effort to avoid. Resources are scarce and authority figures do not have sufficient information to keep everyone as safe as they should. Whether you survive or not comes down to both luck (whether your place and duties precluded you from any other option) and ignorance (whether you picked up a chunk of radioactive graphite with your bare hand). Using PPE is an effort to counteract your ignorance.
Mask wearing was a law in SF during the 1918 epidemic and saved many lives. Once again, history is forgotten.