Cloth face masks to prevent Covid-19 and other respiratory infections.
Magda Milleyde de Sousa Lima, Francisco Marcelo Leandro Cavalcante, Thamires Sales Macêdo and 3 others
PMID 32785565WHAT IT FOUND
Cloth masks filtered some particles in lab studies, but none tested SARS-CoV-2.
Most showed moderate protection; high coverage masks showed high protection. Do not treat this as proof they prevent infection in people.
Key findings
01The review included nine studies, and seven used laboratory tests.
02Cloth facemasks were mostly rated moderate protection, and high coverage masks were rated high protection.
03Mask efficacy depended on fabric, layers, and washing cycles, and the study from Nepal reported a 20% decrease after the fourth washing cycle.
STILL TO COME
How it was doneWhat they foundWhat it means for RNs
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What it does not show
The review did not include studies testing cloth masks against SARS-CoV-2 particles, so it cannot show direct protection from the coronavirus. Most included studies were laboratory tests of particles, not clinical trials in people, so they do not show whether masks prevented respiratory infection in patients. Several studies lacked information about fabric characteristics, so it is hard to apply the results to a specific homemade mask. The clinical trial cited involved health workers in a hospital, not community members, so it does not answer how cloth masks protect patients or families. The conclusion that particle filtering would be similar to protection against SARS-CoV-2 is an inference, not a tested result.
The easy way to misread this
Do not conclude cloth masks prevent SARS-CoV-2 infection in people. The review found no studies testing masks against SARS-CoV-2 particles, and most evidence came from laboratory tests of other particles.