– Policy Brief
Les gouttelettes respiratoires de petites tailles jouent un rôle dans la transmission du SARS-CoV-2. Nous recommandons de réduire la durée des séjours dans les lieux mal ventilés ainsi les activités à forte émission d’aérosols faites à l’intérieur, d’éviter les locaux bondés ainsi que d’assurer une ventilation adéquate des espaces intérieurs.
Il est maintenant reconnu de manière générale que les gouttelettes respiratoires de petite taille – les aérosols – jouent un rôle dans la transmission du SARS-CoV-2. Bien que leur contribution dans la transmission globale reste difficile à quantifier, divers événements de superpropagation indiquent que les aérosols constituent un mode de transmission important dans des environnements intérieurs ayant une mauvaise ventilation, en particulier lors d’activités entraînant des émissions d’aérosols à des taux élevés (comme parler, chanter, crier, faire des activités physiques, etc.). Avec l’arrivée de la saison froide et l’augmentation des activités à l’intérieur, il est possible que les aérosols jouent un rôle plus important dans la transmission du virus. Les mesures bien connues de protection – distanciation physique, hygiène des mains et port de masque – doivent continuer à être largement suivies. L’éloignement physique est important à la fois pour la transmission par gouttelettes et pour celle par aérosols, car les concentrations des deux types de particules diminuent avec la distance de la source. Le port du masque est utile contre les deux types de transmission et devrait être envisagé à l’intérieur également lorsque la distanciation physique de 1,5 m est respectée, notamment lors d’exposition prolongée dans les locaux mal ventilés. Ces mesures additionnelles contribueront à réduire les transmissions par des aérosols spécifiquement:
• assurer une ventilation adéquate des environnements intérieurs avec un apport d’air frais ou correctement filtré;
• éviter les espaces intérieurs bondés;
• réduire le temps passé dans des environnements intérieurs mal ventilés;
• limiter ou annuler les activités à fortes émissions de gouttelettes respiratoires, notamment dans des locaux mal ventilés.
Asadi S, et al. (2019) Aerosol emission and superemission during human speech increase with voice loudness. Scientific Reports, 9, 2348.
Bao L, et al. (2020) Transmission of severe acute respiratory syndrome coronavirus 2 via close contact and respiratory droplets among human angiotensin-converting enzyme 2 mice. Journal of Infectious Diseases, 222, 551-555.
BBC News (October 2020) Coronavirus: Germany improves ventilation to chase away Covid. https://www.bbc.com/news/world-europe-54599593.
Bielecki M, et al. (2020), Social Distancing Alters the Clinical Course of COVID-19 in Young Adults: A Comparative Cohort Study, Clinical Infectious Diseases, https://doi.org/10.1093/cid/ciaa889.
Biggerstaff M, Cauchemez S, Reed C, Gambhir M and Finelly L (2014), Estimates of the reproduction number for seasonal, pandemic, and zoonotic influenza: a systematic review of the literature. BMC Infectious Diseases, 14, Article Number 480.
Chu DK, et al. (2020) Physical distancing, face masks, and eye protection to prevent person-toperson transmission of SARS-CoV-2 and COVID-19: A systematic review and meta-analysis. The Lancet, 395: 1973-1987.
Conly J, et al. (2020) Use of medical face masks versus particulate respirators as a component of personal protective equipment for health care workers in the context of the COVID-19 pandemic. Antimicrobial Resistance and Infection Control, 9,126.
COVID-19 Aerosol Transmission FAQ. Available online: https://tinyurl.com/FAQ-aerosols
Günther T, et al. (2020) Investigation of a superspreading event preceding the largest meat processing plant-related SARS-Coronavirus 2 outbreak in Germany. Preprint available online: https://dx.doi.org/10.2139/ssrn.3654517
Johnson GR, et al. (2011), Modality of human expired aerosol size distributions, Journal of Aerosol
Science 42: 839–851.
Kim YI, et al. (2020) Infection and rapid transmission of SARS-CoV-2 in ferrets. Cell Host and Microbe 27, 704–709.
Klompas M, et al. (2020) Airborne transmission of SARS-CoV-2: theoretical considerations and available evidence. JAMA, 324, 441-442.
Kucharski AJ and Althaus CL (2015) The role of superspreading in Middle East respiratory syndrome coronavirus (MERS-CoV) transmission. Eurosurveillance 20, 21167.
Kupferschmidt, K (2020) Why do some COVID-19 patients infect many others, whereas most don’t
spread the virus at all? Science. http://dx.doi.org/10.1126/science.abc8931
Leclerc QJ, et al. (2020) What settings have been linked to SARS-CoV-2 transmission clusters?
Wellcome Open Research, 5, 83.
Lednicky JA, et al. (2020) Viable SARS-CoV-2 in the air of a hospital room with COVID-19 patients.
MedRxiv preprint available online: https://doi.org/10.1101/2020.08.03.20167395
Li Y, et al. (2020) Evidence for probable aerosol transmission of SARS-CoV-2 in a poorly ventilated
restaurant. MedRxiv preprint available online: https://doi.org/10.1101/2020.04.16.20067728.
Liang M, et al. (2020) Efficacy of face mask in preventing respiratory virus transmission: A systematic review and meta-analysis. Travel Medicine and Infectious Disease: 101751.
Lloyd-Smith J, et al. (2005) Superspreading and the effect of individual variation on disease emergence. Nature 438, 355–359.
Miller SL, et al. (2020) Transmission of SARS-CoV-2 by inhalation of respiratory aerosol in the Skagit Valley Chorale superspreading event. Indoor Air, https://doi.org/10.1111/ina.12751
Morawska LJGR, et al. (2009) Size distribution and sites of origin of droplets expelled from the human respiratory tract during expiratory activities. Journal of Aerosol Science 40.3: 256-269.
Morawska L and Milton DK (2020) It is time to address airborne transmission of coronavirus disease 2019 (COVID-19). Clinical Infectious Diseases, ciaa939, https://doi.org/10.1093/cid/ciaa939
Prather, KA, et al. (2020) Reducing transmission of SARS-CoV-2. Science, 368, 1422-1424.
Richard M, et al. (2020) SARS-CoV-2 is transmitted via contact and via the air between ferrets. Nature Communications, 11, 3496.
Riediker M and Monn C (2020) Simulation of SARS-CoV-2 aerosol emissions in the infected population and resulting airborne exposures in different indoor scenarios. Aerosol and Air Quality Research, https://doi.org/10.4209/aaqr.2020.08.0531
Riediker M and Tsai D (2020) Estimation of viral aerosol emissions from simulated individuals with asymptomatic to moderate coronavirus disease. JAMA Network Open, 3, e2013807.
Riou J and Althaus CL (2020) Pattern of early human-to-human transmission of Wuhan 2019 novel coronavirus (2019-nCoV), December 2019 to January 2020. Eurosurveillance 25, 2000058.
Rudnick SN and Milton DK (2003) Risk of indoor airborne infection transmission estimated from carbon dioxide concentration. Indoor Air, 13, 237-245.
Sia SF, et al. (2020) Pathogenesis and transmission of SARS-CoV-2 in golden hamsters. Nature, 583, 834-838.
Smieszek T, et al. (2019) Assessing the dynamics and control of droplet- and aerosol-transmitted influenza using an indoor positioning system. Scientific Reports, 9, 2185.
Stadnytskyi V, et al. (2020) The airborne lifetime of small speech droplets and their potential importance in SARS-CoV-2 transmission. Proceedings of the National Academy of Sciences USA 117, 11875-11877.
Streeck H, et al. (2020) Infection fatality rate of SARS-CoV-2 infection in a German community with a super-spreading event. MedRxiv preprint available online: https://doi.org/10.1101/2020.05.04.20090076.
Tellier R, Li Y, Cowling BJ and Tang JW (2019) Recognition of aerosol transmission of infectious agents: A commentary. BMC Infectious Diseases, 19, Article number 101.
Ueki H, et al. (2020) Effectiveness of Face Masks in Preventing Airborne Transmission of SARSCoV-2, mSphere, 5, e00637-20.
Umwelt Bundesamt (2020a) Das Risiko einer Übertragung von SARS-CoV-2 in Innenräumen lässt sich durch geeignete Lüftungsmaßnahmen reduzieren.
https://www.umweltbundesamt.de/sites/default/files/medien/2546/dokumente/irk_stellungnahme_lueften_sars-cov-2_0.pdf
Umwelt Bundesamt (2020b) Lüften in Schulen.
https://www.umweltbundesamt.de/sites/default/files/medien/2546/dokumente/umweltbundesamt_lueften_in_schulen_.pdf
Van Doremalen N, et al. (2020) Aerosol and surface stability of SARS-CoV-2 as compared with SARS-CoV-1. New England Journal of Medicine, 382, 1564-1567.
Xie X, et al. (2007) How far droplets can move in indoor environments – revisiting the Wells evaporation–falling curve. Indoor Air, 17, 211-225.
Zhang X and Wang J (2020) Dose-response Relation Deduced for Coronaviruses from COVID-19, SARS and MERS Meta-analysis Results and its Application for Infection Risk Assessment of Aerosol Transmission, Clinical Infectious Diseases, DOI: 10.1093/cid/ciaa1675.
Date of response: 28/11/2020
Expert groups and individuals involved: Roman Stocker, Sarah Tschudin Sutter, Richard Neher, Christian Althaus, Antoine Flahault, and the Exchange group and Infection Prevention and Control group
Contact persons: Roman Stocker, Sarah Tschudin Sutter