Table 1 Parameter values used in the simulation.

Percentage of uninfected persons wearing masks at the outset

Varies by scenario

Mask efficacy as source control:

¹⁴

N95 respirator

96%

Medical procedure mask

56%

Cloth mask

49%

Gaiter

48%

Bandana

33%

Percentage of asymptomatic detected and symptomatic detected COVID-19 cases who adopt mask use

 < 65 years old: 70%

 ≥ 65 years old: 90%

Percentage of symptomatic cases who know they have COVID-19

18.3% (see Supplement)

Average duration of incubation period—other SARS-CoV-2

6 days²³

Delta VOC

4 days^54,55

Omicron VOC

3 days^56,57

Average duration of asymptomatic and symptomatic periods

9 days²³

Relative infectiousness of asymptomatic cases/symptomatic cases

75%²³

Percentage of infections that are asymptomatic

30%²³

Probability of detecting asymptomatic case

10.7% (see Supplement)

Infection Fatality Ratio (IFR)

Ages 0–19: 0.00003

(IFR’s for Delta VOC ≈ 2 × shown for other SARS-CoV-2)^58,59

Ages 20–49: 0.0002

Ages 50–69: 0.005

(IFR’s for Omicron VOC are 0.09 of those for Delta VOC)⁶⁰

Ages 70 + : 0.054²³

Reduction in contact rate for symptomatic and detected asymptomatic persons wearing a mask

50%

Risk of death for symptomatic cases

See Supplement for calculation