Table 3.
Comparison with the convenience no‐mask group
| Arms | CRI | ILI* | Laboratory‐confirmed virus** | Influenza | ||||
|---|---|---|---|---|---|---|---|---|
| N (%) | OR (95% CI)*** | N (%) | OR (95% CI)*** | N (%) | OR (95% CI)*** | N (%) | OR (95% CI)*** | |
| N95 fit‐tested | 21/461 (4·6) | 0·58 (0·18–1·89) P = 0·37 | 1/461 (0·2) | 0·19 (0·02–1·78) P = 0·14 | 8/461 (1·7) | 0·55 (0·22–1·35) P = 0·19 | 3/461 (0·7) | 0·52 (0·13–2·09) P = 0·36 |
| N95 non‐fit‐tested | 16/488 (3·3) | 0·36 (0·14–0·94) P = 0·038 | 2/488 (0·4) | 0·33 (0·06–1·72) P = 0·19 | 5/488 (1) | 0·33 (0·12–0·89) P = 0·03 | 0/488 (0) | 0 – |
| All N95 | 37/949 (3·9) | 0·46 (0·19–1·11) P = 0·085 | 3/949 (0·3) | 0·26 (0·06–1·11) P = 0·068 | 13/949 (1·4) | 0·43 (0·20–0·91) P = 0·02 | 3/949 (0·3) | 0·25 (0·06–1·00) P = 0·051 |
| Medical mask | 33/492 (6·7) | 0·74 (0·29–1·88) P = 0·52 | 3/492 (0·6) | 0·49 (0·12–2·07) P = 0·33 | 13/492 (2·6) | 0·84 (0·38–1·85) P = 0·67 | 5/492 (1) | 0·81 (0·25–2·68) P = 0·73 |
*ILI definition using fever >38 – note, this is less sensitive than laboratory‐confirmed infection.
**Any respiratory virus.
***Odds Ratio – No‐mask convenience group as reference. A random effect logistic model accounting for clustering was used to compute odd ratios.
CRI, clinical respiratory illness; ILI, influenza‐like illness.
Bold text signifies statistical significance.