Table 3.
Outcomes for mask use to prevent viral respiratory tract infections
| MASK USERS | CONFIRMED INFLUENZA | CONFIRMED VIRAL | INFLUENZALIKE ILLNESS | ANY RESPIRATORY INFECTION | ||||
|---|---|---|---|---|---|---|---|---|
|
| ||||||||
| RCTS (N*) | RR† (95% CI) | RCTS (N*) | RR† (95% CI) | RCTS (N*) | RR† (95% CI) | RCTS (N*) | RR† (95% CI) | |
| Community | ||||||||
| • Community members | 2 (1683) | 0.93 (0.50–1.75) | 0 (0) | NA | 2 (1683) | 0.83 (0.69–0.99) | 0 (0) | NA |
| • Families—sick wearing masks | 0 (0) | NA | 1 (597) | 0.98 (0.06–15.54) | 2 (794) | 0.89 (0.48–1.66) | 1 (597) | 0.65 (0.19–2.28) |
| • Families—healthy wearing masks | 1‡ (220) | 2.18 (0.25-19.16) | 1‡ (220) | 2.96 (0.67–13.02) | 1‡ (220) | 1.17 (0.62–2.18) | 0 (0) | NA |
| • Families—healthy and sick wearing masks | 4 (1168) | 0.95 (0.71–1.26) | 0 (0) | NA | 4 (1377) | 1.09 (0.86–1.37) | 0 (0) | NA |
| • Communities staying in tents | 1 (2317) | 1.24 (0.33–4.59) | 2 (2386) | 1.18 (0.79–1.78) | 1 (69) | 0.56 (0.29–1.08) | 1 (1810) | 1.08 (0.83–1.40) |
| • Families—given masks before illness | 0 (0) | NA | 0 (0) | NA | 1 (789) | 0.90 (0.60–1.34) | 0 (0) | NA |
| Health care workers | ||||||||
| • Masks vs nothing | 1 (431) | Not estimable | 1 (431) | 0.90 (0.33–2.44) | 1 (431) | 0.26 (0.01–6.42) | 2 (463) | 0.74 (0.36–1.54) |
| • N95 masks vs surgical masks | 4§ (6039) | 1.10 (0.91–1.32) | 4§ (6059) | 0.95 (0.83–1.07) | 4§ (6662) | 0.78 (0.61–1.00) | 3§ (5033) | 0.95 (0.90–1.00) |
| • Surgical masks vs cloth masks | 1 (717) | 0.98 (0.06–15.62) | 1 (717) | 0.62 (0.31–1.26) | 1 (717) | 0.12 (0.02–0.98) | 1 (717) | 0.62 (0.34–1.11) |
NA—not applicable, RCT—randomized controlled trial, RR—risk ratio.
*
The number of patients is modified (reduced) to account for clustering.
†
Results calculated using a fixed-effects model.
‡
One RCT had 2 arms.
§
Two of the included RCTs had 2 arms, so 4 RCTs would be 6 arms and 3 RCTs would be 5 arms.