A COVID‐19 cluster analysis in an office: Assessing the long‐range aerosol and fomite transmissions with infection control measures

Abstract

Simulated exposure to severe acute respiratory syndrome coronavirus 2 in the environment was demonstrated based on the actual coronavirus disease 2019 cluster occurrence in an office, with a projected risk considering the likely transmission pathways via aerosols and fomites. A total of 35/85 occupants were infected, with the attack rate in the first stage as 0.30. It was inferred that the aerosol transmission at long‐range produced the cluster at virus concentration in the saliva of the infected cases on the basis of the simulation, more than 108 PFU mL−1. Additionally, all wearing masks effectiveness was estimated to be 61%–81% and 88%–95% reduction in risk for long‐range aerosol transmission in the normal and fit state of the masks, respectively, and a 99.8% or above decline in risk of fomite transmission. The ventilation effectiveness for long‐range aerosol transmission was also calculated to be 12%–29% and 36%–66% reductions with increases from one air change per hour (ACH) to two ACH and six ACH, respectively. Furthermore, the virus concentration reduction in the saliva to 1/3 corresponded to the risk reduction for long‐range aerosol transmission by 60%–64% and 40%–51% with and without masks, respectively.

Wind Velocity and Dispersion/Advection-diffusion of Artificial Droplets and Droplet Nuclei in a Domed All- weather Multi-purpose Stadium

“…COVID-19 infection risk assessments have been conducted mainly by the quantitative microbial risk assessment multi-route model 16,17 and the Wells-Riley model 18,19 . The former model has been applied to estimate risk in health care centers 20,21 , o ces 22 , stadiums 23 , subways 24 , and buses 25 . The latter model has been used to assess infection risks in classrooms 26 , hospitals 27 , various other types of facilities 28 , and buses 29 .…”