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Viral Shedding from Persons Infected with SARS-CoV02: Aerosols, Droplet Spray, and Fomites
Oluwasanmi Adenaiye, Jianyu Lai, Filbert Hong, Sheldon Tai, Jennifer German, Somayeh Youssefi, Paul Jacob Bueno de Mesquita, Barbara J. Albert, Tianzhou Ma, Stuart Weston, Matthew B. Frieman, DONALD K. MILTON, School of Public Health, University of Maryland, College Pk
Abstract Number: 570
Working Group: Infectious Aerosols in the Age of COVID-19
Abstract
Background: Characterization of viral shedding into aerosols, droplet spray, and onto fomites is important for understanding SARS-CoV-2 transmission.
Methods: We recruited participants infected with SARS-CoV-2 starting 8 May 2020 through advertising, intensive contact testing, and weekly testing of a community cohort. We collected exhaled coarse (>5µm) and fine (≤5µm) aerosol from cases using a Gesundheit-II (G-II) exhaled breath sampler, mobile phone and mid-turbinate swabs, saliva, and sera; large droplet spray deposited on G-II inlet cone was sampled for cases studied starting 10 September 2020. Samples were tested for viral RNA and cultured for the presence of infectious virus.
Results: As of 30 April 2021, we enrolled 80 persons with presumed or confirmed infection, collected a second sample from 76 on a subsequent day, and have complete qRT-PCR data for 45 confirmed PCR positive cases, seronegative at enrollment, who gave 69 G-II sample visits on days -1 to +7 relative to symptom onset (mean 3.8). Culture data is pending. All cases were ambulatory and mildly symptomatic or asymptomatic at the time of observation. Overall, 36% of cases had viral RNA detected in one or more fine and 29% in coarse aerosol samples, 26% in droplet-spray, and 58% in fomite samples (mobile phone swab) at or above the limit of detection (~75 copies). Most positive samples had only a trace of viral RNA. Samples above the limit of quantification (250 copies) were observed for 18% of cases in fine and 9% in coarse aerosols, 8% in droplet-spray, and 38% in fomite samples.
Conclusion: We observed aerosol shedding in a small fraction of cases, similar to the proportion responsible for the majority of secondary infections. Viral RNA was more frequently observed in aerosols than droplet spray.