Transmission Potential of SARS-CoV-2 in Viral Shedding Observed at the University of Nebraska Medical Center
âDisease spread through both direct (droplet and person-to-person) as well as indirect contact (contaminated objects and airborne transmission) are indicated, supporting the use of airborne isolation precautions.â
"Although this study did not employ any size-fractionation techniques in order to determine the size range of SARS-CoV-2 droplets and particles, the data is suggestive that viral aerosol particles are produced by individuals that have the COVID-19 disease, even in the absence of cough.
First, in the few instances where the distance between individuals in isolation and air sampling could be confidently maintained at greater than 6 ft, 2 of the 3 air samples were positive for viral RNA. Second, 66.7% of hallway air samples indicate that virus-containing particles were being transported from the rooms to the hallway during sampling activities. It is likely that the positive air samples in the hallway were cause by viral aerosol particles transported by personnel exiting the room (16,17). Finally, personal air samplers worn by sampling personnel were all positive for SARS-CoV-2, despite the absence of cough by most patients while sampling personnel were present.
Recent literature investigating human expired aerosol indicates that a significant fraction of human expired aerosol is less than 10 ”m in diameter across all types of activity (e.g. breathing, talking, and coughing; 18) and that upper respiratory illness increases production of aerosol particles (less than 10 ”m; 19). Taken together these results suggest that virus expelled from infected individuals, including from those who are only mildly ill, may be transported by aerosol processes in their local environment, potentially even in the absence of cough or aerosol generating procedures.
Further, a recent study of SARS-CoV-2 in aerosol and deposited on surfaces, indicates infectious aerosol may persist for several hours and on surfaces for as long as 2 days (20).
Despite wide-spread environmental and limited SARS-CoV-2 aerosol contamination associated with hospitalized and mildly ill individuals, effective implementation of airborne isolation precautions including N95 filtering facepiece respirators and powered air purifying respirator use adequately protected health care workers, in the NQU and NBU facilities, preventing health care worker infections.
Health care workers were closely monitored and screened for COVID-19 suggesting the value in implementing IPC protocols that maintain airborne isolation standards including respiratory protection and include routine systematic environmental cleaning and disinfection of patient care areas and surrounding environments."
April 1stâ:wink: