SARS-CoV-2 in Exhaled Aerosol Particles from COVID-19 Cases and Its Association to Household Transmission

Malin Alsved; David Nygren; Sara Thuresson; Patrik Medstrand; Carl Johan Fraenkel; Jakob Löndahl

doi:10.1093/cid/ciac202

SARS-CoV-2 in Exhaled Aerosol Particles from COVID-19 Cases and Its Association to Household Transmission

Clin Infect Dis. 2022 Aug 24;75(1):e50-e56. doi: 10.1093/cid/ciac202.

Authors

Malin Alsved¹, David Nygren², Sara Thuresson¹, Patrik Medstrand³, Carl Johan Fraenkel^{2

4}, Jakob Löndahl¹

Affiliations

¹ Division of Ergonomics and Aerosol Technology, Department of Design Sciences, Lund University, Lund, Sweden.
² Division of Infection Medicine, Department of Clinical Sciences, Lund University, Lund, Sweden.
³ Department of Translational Medicine, Lund University, Lund, Sweden.
⁴ Department of Infection Control, Region Skåne, Lund, Sweden.

Abstract

Background: Coronavirus disease 2019 (COVID-19) transmission via exhaled aerosol particles has been considered an important route for the spread of infection, especially during super-spreading events involving loud talking or singing. However, no study has previously linked measurements of viral aerosol emissions to transmission rates.

Methods: During February-March 2021, COVID-19 cases that were close to symptom onset were visited with a mobile laboratory for collection of exhaled aerosol particles during breathing, talking, and singing, respectively, and of nasopharyngeal and saliva samples. Aerosol samples were collected using a BioSpot-VIVAS and a NIOSH bc-251 2-stage cyclone, and all samples were analyzed by RT-qPCR for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA detection. We compared transmission rates between households with aerosol-positive and aerosol-negative index cases.

Results: SARS-CoV-2 RNA was detected in at least 1 aerosol sample from 19 of 38 (50%) included cases. The odds ratio (OR) of finding positive aerosol samples decreased with each day from symptom onset (OR 0.55, 95 confidence interval [CI] .30-1.0, P = .049). The highest number of positive aerosol samples were from singing, 16 (42%), followed by talking, 11 (30%), and the least from breathing, 3 (8%). Index cases were identified for 13 households with 31 exposed contacts. Higher transmission rates were observed in households with aerosol-positive index cases, 10/16 infected (63%), compared to households with aerosol-negative index cases, 4/15 infected (27%) (χ2 test, P = .045).

Conclusions: COVID-19 cases were more likely to exhale SARS-CoV-2-containing aerosol particles close to symptom onset and during singing or talking as compared to breathing. This study supports that individuals with SARS-CoV-2 in exhaled aerosols are more likely to transmit COVID-19.

Keywords: aerosol sampling; airborne SARS-CoV-2; exhaled aerosol; singing.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

COVID-19* / diagnosis
Family Characteristics
Humans
RNA, Viral
Respiratory Aerosols and Droplets
SARS-CoV-2*

Substances

RNA, Viral