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[quote=Anonymous][quote=Anonymous]Here is a study on the effectiveness of masks generally which also discusses cloth vs. other types of masks, noting that N95 masks are the most effective at prevention but that when there is a shortage of N95 masks or they need to be reserved for health care workers, cloth masks and other types of masks are also effective barriers against Covid infection.  [url]https://www.pnas.org/content/118/4/e2014564118[/url].  Cloth masks were found to be extremely effective in preventing contaminants from a infected person invected with seasonal coronaviruses, influenza, and rhinovirus, though not specifically Covid 19, from being released into the air -- they were effective at filtering out over 97% of contaminants.  They have generally been found to be extremely effective at greatly limiting the spread of an emission cloud from an infected person.  "In summary, there is laboratory-based evidence that household masks have filtration capacity in the relevant particle size range, as well as efficacy in blocking aerosols and droplets from the wearer."

From the perspective of the wearer, the study noted that research "on aerosol exposure has found all types of masks are at least somewhat effective at protecting the wearer.  Vander der Sande et al found that 'all types of masks reduced aerosol exposure, relatively stable over time, unaffected by duration of wear or type of activity,' and concluded that 'any type of general mask use is likely to decrease viral exposure and infection risk on a population level, despite imperfect fit and imperfect adherence."

Also the study notes up front that there are obvious ethical reasons why we do not have controlled studies from the pandemic showing the effectiveness of masks, specifically cloth masks,  vs. no masks against Covid:  "Cochrane (7) and the World Health Organization (8) both point out that, for population health measures, we should not generally expect to be able to find controlled trials, due to logistical and ethical reasons, and should therefore instead seek a wider evidence base. This issue has been identified for studying community use of masks for COVID-19 in particular (9). Therefore, we should not be surprised to find that there is no RCT for the impact of masks on community transmission of any respiratory infection in a pandemic."  In other words, it would be highly unethical to force some people not to wear masks and to give others cloth masks and N95 masks and then expose them to Covid.  No scientist could perform such a study.

PP is looking at the "science" in such a skewed way that s/he is negating all the dozens/hundreds of studies previously performed showing that cloth masks, while not as effective as N95 masks, are still an effective filter against airborne disease generally and requiring something specifically designed to show effectiveness against Covid-19.  Scientists generally recommend cloth masks when better masks aren't available, but PP has "done their own research" ha.

It's the same thing with testing:  scientists generally recommend testing as much as possible including testing asymptomatic people because they still spread Covid.  [/quote]

It is not a randomized control trial, which is what is standard for science.

Highly unethical to do an RCT?!?  We do vaccine RCTs!  That is such a joke of a line.[/quote]

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