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

Abstract

AbstractSimulated 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.