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Size distribution of exhaled aerosol particles containing SARS-CoV-2 RNA

Alsved, Malin LU orcid ; Nygren, David LU orcid ; Thuresson, Sara LU ; Fraenkel, Carl Johan LU ; Medstrand, Patrik LU orcid and Löndahl, Jakob LU orcid (2023) In Infectious Diseases 55(2). p.158-163
Abstract

Background: SARS-CoV-2 in exhaled aerosols is considered an important contributor to the spread of COVID-19. However, characterizing the size distribution of virus-containing aerosol particles has been challenging as high concentrations of SARS-CoV-2 in exhaled air is mainly present close to symptom onset. We present a case study of a person with COVID-19 who was able to participate in extensive measurements of exhaled aerosols already on the day of symptom onset and then for the following three days. Methods: Aerosol collection was performed using an eight-stage impactor while the subject was breathing, talking and singing, for 30 min each, once every day. In addition, nasopharyngeal samples, saliva samples, room air samples and... (More)

Background: SARS-CoV-2 in exhaled aerosols is considered an important contributor to the spread of COVID-19. However, characterizing the size distribution of virus-containing aerosol particles has been challenging as high concentrations of SARS-CoV-2 in exhaled air is mainly present close to symptom onset. We present a case study of a person with COVID-19 who was able to participate in extensive measurements of exhaled aerosols already on the day of symptom onset and then for the following three days. Methods: Aerosol collection was performed using an eight-stage impactor while the subject was breathing, talking and singing, for 30 min each, once every day. In addition, nasopharyngeal samples, saliva samples, room air samples and information on symptom manifestations were collected every day. Samples were analyzed by RT-qPCR for detection of SARS-CoV-2 RNA. Results: SARS-CoV-2 RNA was detected in seven of the eight particle size fractions, from 0.34 to >8.1 µm, with the highest concentrations found in 0.94–2.8 µm particles. The concentration of SARS-CoV-2 RNA was highest on the day of symptom onset, and declined for each day thereafter. Conclusion: Our data showed that 90% of the exhaled SARS-CoV-2 RNA was found in aerosol particles <4.5 µm, indicating the importance of small particles for the transmission of COVID-19 close to symptom onset. These results are important for our understanding of airborne transmission, for developing accurate models and for selecting appropriate mitigation strategies.

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author
; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
cascade impactor, COVID-19, exhaled aerosol, SARS-CoV-2, size distribution
in
Infectious Diseases
volume
55
issue
2
pages
158 - 163
publisher
Informa Healthcare
external identifiers
  • scopus:85141421008
  • pmid:36331347
ISSN
2374-4235
DOI
10.1080/23744235.2022.2140822
language
English
LU publication?
yes
id
018867ed-2bd5-476d-aa87-39960ea5bdb8
date added to LUP
2022-12-20 16:38:23
date last changed
2024-06-13 23:59:49
@article{018867ed-2bd5-476d-aa87-39960ea5bdb8,
  abstract     = {{<p>Background: SARS-CoV-2 in exhaled aerosols is considered an important contributor to the spread of COVID-19. However, characterizing the size distribution of virus-containing aerosol particles has been challenging as high concentrations of SARS-CoV-2 in exhaled air is mainly present close to symptom onset. We present a case study of a person with COVID-19 who was able to participate in extensive measurements of exhaled aerosols already on the day of symptom onset and then for the following three days. Methods: Aerosol collection was performed using an eight-stage impactor while the subject was breathing, talking and singing, for 30 min each, once every day. In addition, nasopharyngeal samples, saliva samples, room air samples and information on symptom manifestations were collected every day. Samples were analyzed by RT-qPCR for detection of SARS-CoV-2 RNA. Results: SARS-CoV-2 RNA was detected in seven of the eight particle size fractions, from 0.34 to &gt;8.1 µm, with the highest concentrations found in 0.94–2.8 µm particles. The concentration of SARS-CoV-2 RNA was highest on the day of symptom onset, and declined for each day thereafter. Conclusion: Our data showed that 90% of the exhaled SARS-CoV-2 RNA was found in aerosol particles &lt;4.5 µm, indicating the importance of small particles for the transmission of COVID-19 close to symptom onset. These results are important for our understanding of airborne transmission, for developing accurate models and for selecting appropriate mitigation strategies.</p>}},
  author       = {{Alsved, Malin and Nygren, David and Thuresson, Sara and Fraenkel, Carl Johan and Medstrand, Patrik and Löndahl, Jakob}},
  issn         = {{2374-4235}},
  keywords     = {{cascade impactor; COVID-19; exhaled aerosol; SARS-CoV-2; size distribution}},
  language     = {{eng}},
  number       = {{2}},
  pages        = {{158--163}},
  publisher    = {{Informa Healthcare}},
  series       = {{Infectious Diseases}},
  title        = {{Size distribution of exhaled aerosol particles containing SARS-CoV-2 RNA}},
  url          = {{http://dx.doi.org/10.1080/23744235.2022.2140822}},
  doi          = {{10.1080/23744235.2022.2140822}},
  volume       = {{55}},
  year         = {{2023}},
}