[BostonCard]

The evidence for masking is copious but circumstantial and mostly observational in nature (and thus not high quality).  I wish there were a cluster randomized trial to prove (or disprove) the benefits of masking and give an estimate of the effect size.  I agree with your skeptical take on masks generally and with the position that social distancing probably does more to prevent transmission than masks.  I think we've gone from "masks may be useful, but the data doesn't really support that" to "masks are probably useful, but the data doesn't prove it".

And when I say "masking in public" I do mean it as a supplement to social distancing, not in lieu of it.  I would wear it indoors out of my house (like at a supermarket) when there are other people around even if there is mostly space to maintain 6 feet.  I would not wear it outdoors unless I was coming up on a group of people and there was a possibility of moving within 6 feet.

One speculative article that has shifted my thinking a bit is this one:

https://www.nejm.org/doi/full/10.1056/NEJMp2026913

SARS-CoV-2 has the protean ability to cause myriad clinical manifestations, ranging from a complete lack of symptoms to pneumonia, acute respiratory distress syndrome, and death. Recent virologic, epidemiologic, and ecologic data have led to the hypothesis that facial masking may also reduce the severity of disease among people who do become infected.3 This possibility is consistent with a long-standing theory of viral pathogenesis, which holds that the severity of disease is proportionate to the viral inoculum received. Since 1938, researchers have explored, primarily in animal models, the concept of the lethal dose of a virus — or the dose at which 50% of exposed hosts die (LD50). With viral infections in which host immune responses play a predominant role in viral pathogenesis, such as SARS-CoV-2, high doses of viral inoculum can overwhelm and dysregulate innate immune defenses, increasing the severity of disease. Indeed, down-regulating immunopathology is one mechanism by which dexamethasone improves outcomes in severe Covid-19 infection. As proof of concept of viral inocula influencing disease manifestations, higher doses of administered virus led to more severe manifestations of Covid-19 in a Syrian hamster model of SARS-CoV-2 infection.4

It is very speculative, but if this does pan out, then masking might not just protect others from asymptomatic carriers, but might protect the wearer, not just by reducing the probability of getting infected, but also by reducing the viral inoculum from an exposure and both reducing the severity of disease and spreading immunity.  It's an angle I hadn't seen before.

BC

[BostonCard]

The evidence for masking is copious but circumstantial and mostly observational in nature (and thus not high quality).  I wish there were a cluster randomized trial to prove (or disprove) the benefits of masking and give an estimate of the effect size.  I agree with your skeptical take on masks generally and with the position that social distancing probably does more to prevent transmission than masks.  I think we've gone from "masks may be useful, but the data doesn't really support that" to "masks are probably useful, but the data doesn't prove it".

And when I say "masking in public" I do mean it as a supplement to social distancing, not in lieu of it.  I would wear it indoors out of my house (like at a supermarket) when there are other people around even if there is mostly space to maintain 6 feet.  I would not wear it outdoors unless I was coming up on a group of people and there was a possibility of moving within 6 feet.

One speculative article that has shifted my thinking a bit is this one:

https://www.nejm.org/doi/full/10.1056/NEJMp2026913

SARS-CoV-2 has the protean ability to cause myriad clinical manifestations, ranging from a complete lack of symptoms to pneumonia, acute respiratory distress syndrome, and death. Recent virologic, epidemiologic, and ecologic data have led to the hypothesis that facial masking may also reduce the severity of disease among people who do become infected.3 This possibility is consistent with a long-standing theory of viral pathogenesis, which holds that the severity of disease is proportionate to the viral inoculum received. Since 1938, researchers have explored, primarily in animal models, the concept of the lethal dose of a virus — or the dose at which 50% of exposed hosts die (LD50). With viral infections in which host immune responses play a predominant role in viral pathogenesis, such as SARS-CoV-2, high doses of viral inoculum can overwhelm and dysregulate innate immune defenses, increasing the severity of disease. Indeed, down-regulating immunopathology is one mechanism by which dexamethasone improves outcomes in severe Covid-19 infection. As proof of concept of viral inocula influencing disease manifestations, higher doses of administered virus led to more severe manifestations of Covid-19 in a Syrian hamster model of SARS-CoV-2 infection.4

It is very speculative, but if this does pan out, then masking might not just protect others from asymptomatic carriers, but might protect the wearer, not just by reducing the probability of getting infected, but also by reducing the viral inoculum from an exposure and both reducing the severity of disease and spreading immunity.  It's an angle I hadn't seen before.

BC