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Effect of mask-wearing on SARS-CoV-2 transmission (number of studies of each type).
| type of | type of | healthcare settings |
community settings |
||||
|---|---|---|---|---|---|---|---|
| comparison | study | lower | no effecta | higher | lower | no effecta | higher |
| mask versus no mask | RCT | 0 | 0 | 0 | 1 | 1 | 0 |
| observational | 19 | 4 | 0 | 20 | 1 | 1 | |
| mask type (higher versus lower quality) | RCT | 0 | 1 | 0 | 1 | 1 | 0 |
| observational | 9 | 5 | 0 | 1 | 1 | 0 | |
| mask mandate | RCT | — | — | — | — | — | — |
| observational | 7 | 1 | 0 | 9 | 1 | 0 | |
| sum | 35 | 11 | 0 | 32 | 5 | 1 | |
aNo statistically significant effect.
