Table 1.
Summary of the evidence for mass masking in mitigating COVID-19 pandemic.
| Evidence | Theme(s) | References |
|---|---|---|
| - Non-pharmaceutical interventions, including population behavioral changes in masking and social distancing, were associated with reduced transmission of COVID-19 and influenza. | A | (10) |
| - Community mask use by well people was suggested to offer protection to healthy individuals especially in high transmission settings. | A | (16) |
| - Presymptomatic transmission contributed to a significant proportion of the COVID-19 transmission. - Control strategies, such as community masking, should be adjusted to tackle presymptomatic transmission. |
B | (17) |
| - Presymptomatic patients with mask-wearing showed significantly lower transmission to close-contact persons. | A, B | (28) |
| - Surgical mask partition reduced transmission of COVID-19 in a hamster model. - Reduction in transmission between the sick and the healthy groups was more significant when the surgical mask partition was placed in the sick hamsters' compartment compared to placing it in the healthy hamsters' compartment. |
A | (29) |
| - Surgical face masks reduced viral RNA in respiratory droplets and aerosols from exhaled breath and coughs. | A, C | (30) |
| - Use of cloth face coverings by both symptomatic patients and healthy individual might reduce the risk of transmission. | A | (31) |
| - The relatively low incidence of COVID-19 in Hong Kong might be contributed by the high compliance of mass masking. - Transmission clusters in ‘mask-off' settings were more prevalent than that in ‘mask-on' settings. |
A | (32) |
| - Airborne transmission was showed to be highly virulent and represented the dominant route to spread the disease in confined environment. - Social distancing alone might be insufficient in protecting the public. - Mandatory face-covering appeared to reduce transmission. |
A, C | (33) |
| - Mask non-wearing rate was shown to be a strong predictor of the numbers of death of COVID-19 pandemic across 22 countries. | D | (34) |
| - Mathematical modeling evaluated that mass masking could reduce total infections and deaths in COVID-19 pandemic. Also, it could delay the peak time of the epidemic. | D, E | (35) |
A, reduction in transmissibility; B, reduction in presymptomatic spread; C, reduction in droplet and aerosol transmission; D, reduction in death rate; E, delay in peak time of the epidemic.