Table 5

HRs from shared frailty Cox proportional hazards model for mask versus no-mask groups (no randomization; n=597)*

HR (95% CI)†
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)RefRefRef
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.