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Jakob Löndahl

Jakob Löndahl

Associate Professor / Senior Lecturer

Jakob Löndahl

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

Summary, in English

BACKGROUND: 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 Feb-Mar 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 two-stage cyclone, and all samples were analyzed by RT-qPCR for 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 one aerosol sample from 19 of 38 (50%) included cases. The odds ratio of finding positive aerosol samples decreased with each day from symptom onset (OR 0.55, 95CI 0.30-1.0, p=0.049). 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%) (Chi-square test, p=0.045).

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.


  • Ergonomics and Aerosol Technology
  • Metalund
  • NanoLund: Center for Nanoscience
  • Translational infection medicine
  • EpiHealth: Epidemiology for Health
  • Clinical Virology, Malmö
  • Infection Medicine (BMC)

Publishing year







Clinical infectious diseases : an official publication of the Infectious Diseases Society of America





Document type

Journal article


Oxford University Press


  • Infectious Medicine



Research group

  • Translational infection medicine
  • Clinical Virology, Malmö


  • ISSN: 1537-6591