HRs from shared frailty Cox proportional hazards model for mask versus no-mask groups (no randomization; n=597)*
| CRI HR (95% CI)† | ILI HR (95% CI)† | Laboratory-confirmed viral respiratory infections HR (95% CI)† | |
|---|---|---|---|
| Masks group (index case) | 0.22 (0.06 to 0.86) | 0.18 (0.02 to 1.73) | 0.11 (0.01 to 4.40) |
| No-mask group (index case) | Ref | Ref | Ref |
| Age (household) | 1.03 (1.00 to 1.06) |
Bold values are statistically significant results.
*Household members (mask group 387 and no-mask group 210).
†Multivariate analysis was performed as there were 10 cases of CRI and age was also significant in the univariate analysis. Multivariate analyses were not performed for ILI and laboratory-confirmed viral respiratory infections due to the low number of cases.
CRI, clinical respiratory illness; ILI, influenza-like illness.