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Viral load of SARS-CoV-2 in droplets and bioaerosols directly captured during breathing, speaking and coughing.

Published version
Peer-reviewed

Type

Article

Change log

Authors

Johnson, Tyler J 
Nishida, Robert T 
Lin, Yi-Chan James 
Watson, Kimberley A 

Abstract

Determining the viral load and infectivity of SARS-CoV-2 in macroscopic respiratory droplets, bioaerosols, and other bodily fluids and secretions is important for identifying transmission modes, assessing risks and informing public health guidelines. Here we show that viral load of SARS-CoV-2 Ribonucleic Acid (RNA) in participants' naso-pharyngeal (NP) swabs positively correlated with RNA viral load they emitted in both droplets >10 [Formula: see text] and bioaerosols <10 [Formula: see text] directly captured during the combined expiratory activities of breathing, speaking and coughing using a standardized protocol, although the NP swabs had [Formula: see text] 10[Formula: see text] more RNA on average. By identifying highly-infectious individuals (maximum of 18,000 PFU/mL in NP), we retrieved higher numbers of SARS-CoV-2 RNA gene copies in bioaerosol samples (maximum of 4.8[Formula: see text] gene copies/mL and minimum cycle threshold of 26.2) relative to other studies. However, all attempts to identify infectious virus in size-segregated droplets and bioaerosols were negative by plaque assay (0 of 58). This outcome is partly attributed to the insufficient amount of viral material in each sample (as indicated by SARS-CoV-2 gene copies) or may indicate no infectious virus was present in such samples, although other possible factors are identified.

Description

Keywords

Aerosols, Cough, Humans, Respiration, SARS-CoV-2, Speech, Viral Load

Journal Title

Sci Rep

Conference Name

Journal ISSN

2045-2322
2045-2322

Volume Title

12

Publisher

Springer Science and Business Media LLC
Sponsorship
Natural Sciences and Engineering Research Council of Canada (Postdoctoral Fellowships Program)
World Health Organization (Research grant for the Infection Prevention and Control (IPC) Pillar.)