I still don’t understand your model. Do you think that almost all COVID-19 infections occur by face-touching, and almost none by droplets directly landing on someone’s face? (If so what’s your evidence?) Because masks protect against both, whereas handwashing only protects against the former. It seems if we have 100% compliance with masks that would be more effective than 100% compliance of even very high frequency of handwashing (which would also be a lot more costly for people to follow). Do you disagree with this? (If so, this might be our major crux.)
ETA: Masks don’t protect against rubbing eyes, but we can fix that by telling people to also wear goggles. Also it seems a lot easier to achieve 100% compliance with masks/goggles (at least when supplies are adequate) because it’s visible and we can attach social stigma to people who don’t comply.
“Do you think that almost all COVID-19 infections occur by face-touching, and almost none by droplets directly landing on someone’s face?”
Not almost none, but very few, yes. Aerosol transmissions are a thing, but for non airborne transmissible diseases, these seem to be rare compared to close-personal interaction transmissions, such as direct hand contact and touching other people or shared surfaces.
EDIT TO NOTE: I have changed my understanding of this. The problem was that I misunderstood terminology—papers saying there is not “aerosol” transmission don’t include droplet transmission via droplets that float in the air for up to an hour, from potentially several meters away, which I misunderstood.
Mask usage is great for reducing the rate that already sick people infect others, but not recommended for healthy people, because it’s just not that effective. Sick people should be quarantined, which is far more effective. Perhaps 100% compliance with mask wearing would be a viable secondary measure, if there were sufficient supply for at least sick people (there aren’t even that many,) and if it were plausible to be fully compliant—but mask usage is necessarily impossible when eating and when drinking, which people need to do routinely, and hand-washing if going to be still useful and particularly critical at those times. (And no, homemade masks aren’t as effective, and masks shouldn’t really be reused.)
EDIT TO NOTE: Because presymptomatic and asymptomatic transmission is a thing, mask wearing is likely useful to prevent transmitting the disease to others. It’s still not clear that there is any benefit for healthy people, but since we don’t know who is healthy, that’s basically irrelevant.
Can you say why you believe “very few” infections occur by droplets directly landing on someone’s face? The CDC says:
“The virus is thought to spread mainly from person-to-person, Between people who are in close contact with one another (within about 6 feet), Through respiratory droplets produced when an infected person coughs or sneezes. These droplets can land in the mouths or noses of people who are nearby or possibly be inhaled into the lungs.
...It may be possible that a person can get COVID-19 by touching a surface or object that has the virus on it and then touching their own mouth, nose, or possibly their eyes, but this is not thought to be the main way the virus spreads.”
i.e. (as I read this) handwashing would help with a hypothetical, secondary mode of transmission, whereas properly-fitted masks / goggles would presumably help reduce the primary mode of transmission. This is consistent with a couple other sources I’ve seen, but I haven’t delved into the literature.
I have updated strongly towards agreeing with you given research in the past 2 weeks, but transmissions are clearly happening both ways—it’s not hypothetical.
Not almost none, but very few, yes. Aerosol transmissions are a thing, but for non airborne transmissible diseases, these seem to be rare compared to close-personal interaction transmissions, such as direct hand contact and touching other people or shared surfaces.
They said the study proves the importance of washing hands and wearing face masks in public places because the virus can linger in the air attached to fine droplet particles.
“Our advice is to wear a face mask all the way [through the bus ride],” they added.
[...] The researchers also found that none of those passengers in the two buses who wore face masks were infected.
They said it vindicated the decision to ask people to wear a face mask in public.
I still don’t understand your model. Do you think that almost all COVID-19 infections occur by face-touching, and almost none by droplets directly landing on someone’s face? (If so what’s your evidence?) Because masks protect against both, whereas handwashing only protects against the former. It seems if we have 100% compliance with masks that would be more effective than 100% compliance of even very high frequency of handwashing (which would also be a lot more costly for people to follow). Do you disagree with this? (If so, this might be our major crux.)
ETA: Masks don’t protect against rubbing eyes, but we can fix that by telling people to also wear goggles. Also it seems a lot easier to achieve 100% compliance with masks/goggles (at least when supplies are adequate) because it’s visible and we can attach social stigma to people who don’t comply.
“Do you think that almost all COVID-19 infections occur by face-touching, and almost none by droplets directly landing on someone’s face?”
Not almost none, but very few, yes. Aerosol transmissions are a thing, but for non airborne transmissible diseases, these seem to be rare compared to close-personal interaction transmissions, such as direct hand contact and touching other people or shared surfaces.
EDIT TO NOTE: I have changed my understanding of this. The problem was that I misunderstood terminology—papers saying there is not “aerosol” transmission don’t include droplet transmission via droplets that float in the air for up to an hour, from potentially several meters away, which I misunderstood.
Mask usage is great for reducing the rate that already sick people infect others, but not recommended for healthy people, because it’s just not that effective. Sick people should be quarantined, which is far more effective. Perhaps 100% compliance with mask wearing would be a viable secondary measure, if there were sufficient supply for at least sick people (there aren’t even that many,) and if it were plausible to be fully compliant—but mask usage is necessarily impossible when eating and when drinking, which people need to do routinely, and hand-washing if going to be still useful and particularly critical at those times. (And no, homemade masks aren’t as effective, and masks shouldn’t really be reused.)
EDIT TO NOTE: Because presymptomatic and asymptomatic transmission is a thing, mask wearing is likely useful to prevent transmitting the disease to others. It’s still not clear that there is any benefit for healthy people, but since we don’t know who is healthy, that’s basically irrelevant.
Can you say why you believe “very few” infections occur by droplets directly landing on someone’s face? The CDC says:
“The virus is thought to spread mainly from person-to-person, Between people who are in close contact with one another (within about 6 feet), Through respiratory droplets produced when an infected person coughs or sneezes. These droplets can land in the mouths or noses of people who are nearby or possibly be inhaled into the lungs.
...It may be possible that a person can get COVID-19 by touching a surface or object that has the virus on it and then touching their own mouth, nose, or possibly their eyes, but this is not thought to be the main way the virus spreads.”
i.e. (as I read this) handwashing would help with a hypothetical, secondary mode of transmission, whereas properly-fitted masks / goggles would presumably help reduce the primary mode of transmission. This is consistent with a couple other sources I’ve seen, but I haven’t delved into the literature.
I have updated strongly towards agreeing with you given research in the past 2 weeks, but transmissions are clearly happening both ways—it’s not hypothetical.
Ooh, what did you read? Can you suggest any links?
Just came across this story Coronavirus can travel twice as far as official ‘safe distance’ and stay in air for 30 minutes, Chinese study finds:
I think they can if done properly.
FYI, that first article you linked was later retracted without explanation.