Table 1b Efficacy of surgical face masks in reducing respiratory virus frequency of detection and viral shedding in respiratory droplets and aerosols of symptomatic individuals with coronavirus, influenza virus or rhinovirus infection

From: Respiratory virus shedding in exhaled breath and efficacy of face masks

  Droplet particles >5 μm Aerosol particles ≤5 μm
Virus type Without surgical face mask With surgical face mask P Without surgical face mask With surgical face mask P
  Detection of virus
No. positive/no. total (%) No. positive/no. total (%)   No. positive/no. total (%) No. positive/no. total (%)  
Coronavirus 3 of 10 (30) 0 of 11 (0) 0.09 4 of 10 (40) 0 of 11 (0) 0.04
Influenza virus 6 of 23 (26) 1 of 27 (4) 0.04 8 of 23 (35) 6 of 27 (22) 0.36
Rhinovirus 9 of 32 (28) 6 of 27 (22) 0.77 19 of 34 (56) 12 of 32 (38) 0.15
  Viral load (log10 virus copies per sample)
Median (IQR) Median (IQR)   Median (IQR) Median (IQR)  
Coronavirus 0.3 (0.3, 1.2) 0.3 (0.3, 0.3) 0.07 0.3 (0.3, 3.3) 0.3 (0.3, 0.3) 0.02
Influenza virus 0.3 (0.3, 1.1) 0.3 (0.3, 0.3) 0.01 0.3 (0.3, 3.0) 0.3 (0.3, 0.3) 0.26
Rhinovirus 0.3 (0.3, 1.3) 0.3 (0.3, 0.3) 0.44 1.8 (0.3, 2.8) 0.3 (0.3, 2.4) 0.12
  1. P values for comparing the frequency of respiratory virus detection between the mask intervention were obtained by two-sided Fisher’s exact test and (two-sided) P values for mask intervention as predictor of log10 virus copies per sample were obtained by an unadjusted univariate Tobit regression model, which allowed for censoring at the lower limit of detection of the RT–PCR assay, with significant differences in bold. Undetectable values were imputed as 0.3 log10 virus copies per sample. IQR, interquartile range.