A big problem with all the discussion about masks is that there are at least three different types of study, and people tend to mix the conclusions.
1. Epidemiological: "Town A mandated masks and town B didn't. Was there any difference in reported rate of pathogen spread?" Reviews over the past century of epidemic responses indicated no overall benefit.
2. Clinical: "In a controlled situation, was there a difference in rate of pathogen spread between the mask-user group and the non-mask group?" There was soft support for some benefit in non-sterile, close-contact environments.
3. Laboratory: "On a laboratory bench, what degree of pathogen capture was achieved by the mask apparatus?" These studies assume that performance on the bench correlates to performance in the field. The N95 mask is a case in point. On the bench, it performs better, but reviews of clinical studies didn't find a strong effect in field use.
1. Epidemiological: "Town A mandated masks and town B didn't. Was there any difference in reported rate of pathogen spread?" Reviews over the past century of epidemic responses indicated no overall benefit.
2. Clinical: "In a controlled situation, was there a difference in rate of pathogen spread between the mask-user group and the non-mask group?" There was soft support for some benefit in non-sterile, close-contact environments.
3. Laboratory: "On a laboratory bench, what degree of pathogen capture was achieved by the mask apparatus?" These studies assume that performance on the bench correlates to performance in the field. The N95 mask is a case in point. On the bench, it performs better, but reviews of clinical studies didn't find a strong effect in field use.