Impact of face coverings on Infection Risk Score
We then assessed the impact of the use of face coverings in retail outlets and on public transport on the overall IRS, using the four different degrees of effectivenesses of face coverings in reducing transmission, namely 20%, 40%, 60% and 80%. Table 1 shows that risk score reduced from 58.9 to 58.0 (1.5% reduction in overall risk) for a face covering-associated efficacy of 20%, to 57.2 (2.9% reduction in overall risk) for an efficacy of 40%, to 56.3 (4.4% reduction in overall risk) for an efficacy of 60%, and to 55.5 (5.8% reduction in overall risk) for an efficacy of 80%. A surgical mask, as used in hospitals, with an efficacy of over 90% would only reduce overall risk by 6.6% up to the maximum 7.3%.