The size and culturability of patient-generated SARS-CoV-2 aerosol

Abstract

Background Aerosol transmission of COVID-19 is the subject of ongoing policy debate. Characterizing aerosol produced by people with COVID-19 is critical to understanding the role of aerosols in transmission. Objective We investigated the presence of virus in size-fractioned aerosols from six COVID-19 patients admitted into mixed acuity wards in April of 2020. Methods Size-fractionated aerosol samples and aerosol size distributions were collected from COVID-19 positive patients. Aerosol samples were analyzed for viral RNA, positive samples were cultured in Vero E6 cells. Serial RT-PCR of cells indicated samples where viral replication was likely occurring. Viral presence was also investigated by western blot and transmission electron microscopy (TEM). Results SARS-CoV-2 RNA was detected by rRT-PCR in all samples. Three samples confidently indicated the presence of viral replication, all of which were from collected sub-micron aerosol. Western blot indicated the presence of viral proteins in all but one of these samples, and intact virions were observed by TEM in one sample. Significance Observations of viral replication in the culture of submicron aerosol samples provides additional evidence that airborne transmission of COVID-19 is possible. These results support the use of efficient respiratory protection in both healthcare and by the public to limit transmission.

Aerosol tracer testing in Boeing 767 and 777 aircraft to simulate exposure potential of infectious aerosol such as SARS-CoV-2

“…The CDC has determined that airborne transmission of SARS-CoV-2 can occur in environments which include enclosed spaces, prolonged exposure, and inadequate ventilation [ 2 ], which raises questions as to prolonged contact in an aircraft cabin environment. While projectile droplet transmission, dominated by their own inertia, likely does not vary substantially from the unique circumstance of being on an aircraft, the aerosol exposure route for smaller droplets and evaporated droplet nuclei is dependent on the ventilation, environment, and exposure time [ 3 , 4 ]. A variety of research supports this conclusion, including sampling infectious virus in the air [ 4 , 5 ], and case studies suggesting aerosol transmission [ 6 – 8 ].…”

“…While projectile droplet transmission, dominated by their own inertia, likely does not vary substantially from the unique circumstance of being on an aircraft, the aerosol exposure route for smaller droplets and evaporated droplet nuclei is dependent on the ventilation, environment, and exposure time [ 3 , 4 ]. A variety of research supports this conclusion, including sampling infectious virus in the air [ 4 , 5 ], and case studies suggesting aerosol transmission [ 6 – 8 ]. An example of the latter occurred in a poorly ventilated nursing home unit where 81% of patients and 50% of staff became infected.…”

COVID-19: the case for aerosol transmission

“…Finally, Santarpia et al [ 44 ] also demonstrated the presence of infectious SARS-CoV-2 in aerosol samples. Using a NIOSH BC25 sampler the authors collected aerosols samples in five patient rooms in two different hospital wards; the samples were size-segregated in three groups: greater than 4.1 µm, 1–4 µm and less than 1 µm.…”

Evidence of Air and Surface Contamination with SARS-CoV-2 in a Major Hospital in Portugal

“…Airborne transmission of SARS-CoV-2 is now widely accepted as a mode of transmission of SARS-CoV-2 [ 2 , 4 , 8 , 12 ]. This route dominates under certain environmental conditions, particularly indoor environments without proper ventilation [ 24 , 25 , 26 , 27 , 28 , 29 ], with a recent study demonstrating that some fraction of the RNA-containing aerosols emitted from infected people contain intact, replication-competent virions [ 30 ]. On the contrary, current evidence suggests that transmission through contaminated surfaces is rare; however, when it comes to healthcare settings where COVID-19 patients are being treated, especially in ICUs, aerosol-generating medical procedures take place which could potentially exacerbate the contamination of air and surfaces in the surrounding area [ 31 ].…”