Risk for transmission of viral infection during treatment with nebuliser or high-flow nasal cannula

Viral infections caused by SARS-CoV-2, SARS-CoV-1 or MERS-CoV can lead to severe respiratory failure and the need for hospital care. There is a concern that treatment with nebuliser or high-flow nasal cannula may present an increased risk for transmission of infectious diseases trough the production and spread of aerosols.


What scientific studies are there on 1) risk for transmission of SARS-CoV-2, SARS-CoV-1 or MERS-CoV infections and 2) spread of aerosols during treatment with nebuliser or high-flow nasal cannula? 


SBU’s Enquiry Service identifies and summarizes systematic reviews or scientific studies which answer specific questions posed by decision makers and health care personnel. For this question, PubMed, Embase, Cinahl and Cochrane Library were systematically searched in April 29, 2020, and supplemented by manual searching of reference lists. Records relevant to the question posed were identified and assessed for risk of bias by two independent persons. The identified primary studies were assessed for risk of bias using translated versions of RoB-2 [1] and ROBINS-I [2]. Studies without control groups were assessed for methodological concerns through a customized checklist. The results of the identified studies were not synthesized or assessed for certainty of evidence.

Identified literature

One systematic review and five primary studies were identified that investigated risk for transmission of SARS-CoV-2, SARS-CoV-1 or MERS-CoV in association to treatment with nebuliser [3–8]. All primary studies were judged to have a high risk of bias from confounders and retrospective data collection. No study was identified that investigated risk of transmission in association to treatment with high-flow nasal cannula.

17 studies were identified that investigated spread of aerosols from nebulisers or high-flow nasal cannulas. 7 of the studies were performed in a hospital environment involving patients or healthy persons [9–15], and 10 of the studies were experimental model studies involving human simulators [16–25]. The studies were heterogenous regarding outcome, method of measuring and distance to the source. Only clinical studies were assessed for risk of bias.


  1. Sterne JAC, Savović J, Page MJ, Elbers RG, Blencowe NS, Boutron I, et al. RoB 2: a revised tool for assessing risk of bias in randomised trials. Bmj 2019;366:l4898.
  2. Sterne JA, Hernán MA, Reeves BC, Savović J, Berkman ND, Viswanathan M, et al. ROBINS-I: a tool for assessing risk of bias in non-randomised studies of interventions. BMJ 2016;355:i4919.
  3. Heinzerling A, Stuckey MJ, Scheuer T, Xu K, Perkins KM, Resseger H, et al. Transmission of COVID-19 to health care personnel during exposures to a hospitalized patient - Solano County, California, February 2020. MMWR Morb Mortal Wkly Rep 2020;69:472-6.
  4. Loeb M, McGeer A, Henry B, Ofner M, Rose D, Hlywka T, et al. SARS among critical care nurses, Toronto. Emerg Infect Dis 2004;10:251-5.
  5. Raboud J, Shigayeva A, McGeer A, Bontovics E, Chapman M, Gravel D, et al. Risk factors for SARS transmission from patients requiring intubation: a multicentre investigation in Toronto, Canada. PLoS One 2010;5:e10717.
  6. Tran K, Cimon K, Severn M, Pessoa-Silva CL, Conly J. Aerosol generating procedures and risk of transmission of acute respiratory infections to healthcare workers: A systematic review. PLoS ONE 2012;7.
  7. Wong TW, Lee CK, Tam W, Lau JT, Yu TS, Lui SF, et al. Cluster of SARS among medical students exposed to single patient, Hong Kong. Emerg Infect Dis 2004;10:269-76.
  8. Yu IT, Zhan HX, Tsoi KK, Yuk LC, Siu WL, Xiao PT, et al. Why did outbreaks of severe acute respiratory syndrome occur in some hospital wards but not in others? Clin Infect Dis 2007;44:1017-25.
  9. He C, Mackay IM, Ramsay K, Liang Z, Kidd T, Knibbs LD, et al. Particle and bioaerosol characteristics in a paediatric intensive care unit. Environment International 2017;107:89-99.
  10. Jones AM, Govan JR, Doherty CJ, Dodd ME, Isalska BJ, Stanbridge TN, et al. Identification of airborne dissemination of epidemic multiresistant strains of Pseudomonas aeruginosa at a CF centre during a cross infection outbreak. Thorax 2003;58:525-7.
  11. Leung CCH, Joynt GM, Gomersall CD, Wong WT, Lee A, Ling L, et al. Comparison of high-flow nasal cannula versus oxygen face mask for environmental bacterial contamination in critically ill pneumonia patients: a randomized controlled crossover trial. J Hosp Infect 2019;101:84-7.
  12. O'Neil CA, Li J, Leavey A, Wang Y, Hink M, Wallace M, et al. Characterization of aerosols generated during patient care activities. Clinical Infectious Diseases 2017;65:1342-1348.
  13. Simonds AK, Hanak A, Chatwin M, Morrell M, Hall A, Parker KH, et al. Evaluation of droplet dispersion during non-invasive ventilation, oxygen therapy, nebuliser treatment and chest physiotherapy in clinical practice: implications for management of pandemic influenza and other airborne infections. Health technology assessment (Winchester, England) 2010;14:131-172.
  14. Thompson K, Thomson G, Mittal H, Parks S, Dove B, Speight S, et al. Transmission of influenza to health-care workers in intensive care units - Could Aerosol generating procedures play a role? Journal of Hospital Infection 2010;76:S5.
  15. Wan GH, Tsai YH, Wu YK, Tsao KC. A large-volume nebulizer would not be an infectious source for severe acute respiratory syndrome. Infect Control Hosp Epidemiol 2004;25:1113-5.
  16. Bennett G, O'Toole C, Joyce M, McGrath J, Byrne M, MacLoughlin R. Effect of tidal volume on fugitive emissions during mechanical ventilation. Eur Respir J 2018;52.
  17. Hui DS, Chow BK, Chu LCY, Ng SS, Hall SD, Gin T, et al. Exhaled air and aerosolized droplet dispersion during application of a jet nebulizer. Chest 2009;135:648-54.
  18. Leonard S, Atwood CW, Walsh BK, DeBellis RJ, Dungan GC, Strasser W, et al. Preliminary Findings of Control of Dispersion of Aerosols and Droplets during High Velocity Nasal Insufflation Therapy Using a Simple Surgical Mask: Implications for High Flow Nasal Cannula. Chest 2020.
  19. McGrath JA, O'Sullivan A, Bennett G, O'Toole C, Joyce M, Byrne MA, et al. Investigation of the Quantity of Exhaled Aerosols Released into the Environment during Nebulisation. Pharmaceutics 2019;11.
  20. McGrath JA, O'Toole C, Bennett G, Joyce M, Byrne MA, MacLoughlin R. Investigation of Fugitive Aerosols Released into the Environment during High-Flow Therapy. Pharmaceutics 2019;11.
  21. Hui DS, Chan MT, Chow B. Aerosol dispersion during various respiratory therapies: a risk assessment model of nosocomial infection to health care workers. Hong Kong Med J 2014;20 Suppl 4:9-13.
  22. Ari A FJ, Pilbeam S. Secondhand aerosol exposure during mechanical ventilation with and without expiratory filters: An in-vitro study. Ind J Resp Care 2016;5:677-83.
  23. Hui DS, Chow BK, Lo T, Tsang OTY, Ko FW, Ng SS, et al. Exhaled air dispersion during high-flow nasal cannula therapy versus CPAP via different masks. Eur Respir J 2019;53.
  24. Kotoda M, Hishiyama S, Mitsui K, Tanikawa T, Morikawa S, Takamino A, et al. Assessment of the potential for pathogen dispersal during high-flow nasal therapy. J Hosp Infect 2020;104:534-7.
  25. Hui DS, Chow BK, Chu L, Ng SS, Lai ST, Gin T, et al. Exhaled air dispersion and removal is influenced by isolation room size and ventilation settings during oxygen delivery via nasal cannula. Respirology 2011;16:1005-13.

SBU Enquiry Service Consists of structured literature searches to highlight studies that can address questions received by the SBU Enquiry Service from Swedish healthcare or social service providers. We assess the risk of bias in systematic reviews and when needed also quality and transferability of results in health economic studies. Relevant references are compiled by an SBU staff member, in consultation with an external expert when needed.

Published: 6/8/2020
Report no: ut202022
Registration no: SBU 2020/449