Airborne transmission of severe acute respiratory syndrome coronavirus‐2 to healthcare workers: a narrative review

Anaesthesia - Tập 75 Số 8 - Trang 1086-1095 - 2020
Nick Wilson1, A. Norton2, Francis Young1, David W. Collins1
1Department of Intensive Care Medicine, Prince of Wales Hospital, Sydney, NSW, Australia
2Emergency Department, Oamaru Hospital, New Zealand

Tóm tắt

SummaryHealthcare workers are at risk of infection during the severe acute respiratory syndrome coronavirus‐2 pandemic. International guidance suggests direct droplet transmission is likely and airborne transmission occurs only with aerosol‐generating procedures. Recommendations determining infection control measures to ensure healthcare worker safety follow these presumptions. Three mechanisms have been described for the production of smaller sized respiratory particles (‘aerosols’) that, if inhaled, can deposit in the distal airways. These include: laryngeal activity such as talking and coughing; high velocity gas flow; and cyclical opening and closure of terminal airways. Sneezing and coughing are effective aerosol generators, but all forms of expiration produce particles across a range of sizes. The 5‐μm diameter threshold used to differentiate droplet from airborne is an over‐simplification of multiple complex, poorly understood biological and physical variables. The evidence defining aerosol‐generating procedures comes largely from low‐quality case and cohort studies where the exact mode of transmission is unknown as aerosol production was never quantified. We propose that transmission is associated with time in proximity to severe acute respiratory syndrome coronavirus‐1 patients with respiratory symptoms, rather than the procedures per se. There is no proven relation between any aerosol‐generating procedure with airborne viral content with the exception of bronchoscopy and suctioning. The mechanism for severe acute respiratory syndrome coronavirus‐2 transmission is unknown but the evidence suggestive of airborne spread is growing. We speculate that infected patients who cough, have high work of breathing, increased closing capacity and altered respiratory tract lining fluid will be significant producers of pathogenic aerosols. We suggest several aerosol‐generating procedures may in fact result in less pathogen aerosolisation than a dyspnoeic and coughing patient. Healthcare workers should appraise the current evidence regarding transmission and apply this to the local infection prevalence. Measures to mitigate airborne transmission should be employed at times of risk. However, the mechanisms and risk factors for transmission are largely unconfirmed. Whilst awaiting robust evidence, a precautionary approach should be considered to assure healthcare worker safety.

Từ khóa


Tài liệu tham khảo

10.3201/eid1002.030793

10.1164/rccm.200305-715OC

10.1378/chest.126.3.845

10.3201/eid1002.030838

10.3201/eid1002.030534

10.3201/eid1002.030700

World Health Organisation.Modes of transmission of virus causing COVID‐19: implications for IPC precaution recommendations.2020.https://www.who.int/news-room/commentaries/detail/modes-of-transmission-of-virus-causing-covid-19-implications-for-ipc-precaution-recommendations(accessed 08/04/2020).

10.1053/j.gastro.2020.02.054

10.1371/journal.pone.0035797

10.1016/j.ajic.2016.06.003

10.1152/japplphysiol.00873.2009

10.1373/clinchem.2011.169235

10.1080/15459624.2012.684582

10.1080/15459624.2014.973113

10.1086/596478

10.1371/journal.ppat.1003205

10.1093/infdis/jiy221

10.1016/j.jhin.2014.11.005

10.1073/pnas.0408159101

10.1016/j.medengphy.2017.03.004

10.1016/j.jaerosci.2011.07.009

10.1016/j.jinf.2010.11.010

Hinds WC, 1999, Aerosol Technology: Properties, Behavior, and Measurement of Airborne Particles

10.1111/j.1600-0668.2007.00469.x

10.3201/eid1211.060426

10.1038/213095a0

10.1017/S0022172400019288

10.1089/jam.1997.10.105

10.1186/s12931-019-0970-9

Bourouiba L, 2020, Turbulent gas clouds and respiratory pathogen emissions: potential implications for reducing transmission of COVID‐19, Journal of the American Medical Association, 323, 1837

10.1056/NEJMoa032867

10.1001/jama.1936.02770470016004

10.1128/JVI.03544-13

Hui DSC, 2014, Aerosol dispersion during various respiratory therapies: a risk assessment model of nosocomial infection to health care workers, Hong Kong Medical Journal, 20, 9

10.1093/cid/cix535

10.3181/00379727-122-31255

10.1093/infdis/154.4.709

10.3181/00379727-53-14251P

10.1038/ncomms2922

10.1098/rsif.2010.0686

10.3201/eid1002.030452

10.1086/429634

10.1002/path.1570

10.1007/s00134-020-05985-9

10.1056/NEJMc2004973

10.1001/jama.2020.3227

10.1371/journal.pone.0056278

10.1093/ofid/ofx162.085

10.1152/japplphysiol.01179.2001

10.1172/JCI106015

10.1097/MCC.0000000000000691

10.1111/anae.15054

10.1183/13993003.02339-2018

10.1111/anae.15054

10.1111/anae.15073

Zhejiang University School of Medicine.Handbook of COVID‐19 Prevention and Treatment.2020.https://iau-aiu.net/Zhejiang-University-Handbook-of-COVID-19-Prevention-and-Treatment(accessed 28/03/2020).

10.1186/s13613-020-00653-z

10.1038/s41368-020-0074-x

Thông tin
Thông tin xuất bản

Anaesthesia

Tập 75 Số 8

1086-1095

Thông tin tác giả