Outdoor transmission of SARS-CoV-2 and other respiratory viruses: a systematic review
Open accessAbstract
Background: While risk of outdoor transmission of respiratory viral infections is hypothesized to be low, there are limited data on SARS-CoV-2 transmission in outdoor compared to indoor settings. Methods: We conducted a systematic review of peer-reviewed papers indexed in PubMed, EMBASE, and Web of Science and preprints in Europe PMC through 12 August 2020 that described cases of human transmission of SARS-CoV-2. Reports of other respiratory virus transmission were included for reference. Results: Five identified studies found a low proportion of reported global SARS-CoV-2 infections occurred outdoors (<10%) and the odds of indoor transmission was very high compared to outdoors (18.7 times; 95% confidence interval, 6.0–57.9). Five studies described influenza transmission outdoors and 2 adenovirus transmission outdoors. There was high heterogeneity in study quality and individual definitions of outdoor settings, which limited our ability to draw conclusions about outdoor transmission risks. In general, factors such as duration and frequency of personal contact, lack of personal protective equipment, and occasional indoor gathering during a largely outdoor experience were associated with outdoor reports of infection. Conclusions: Existing evidence supports the wide-held belief that risk of SARS-CoV-2 transmission is lower outdoors but there are significant gaps in our understanding of specific pathways.
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Cites
Rayyan-a web and mobile app for systematic reviews.
Ouzzani, M., Hammady, H., Fedorowicz, Z., & Elmagarmid, A. (2016) · Systematic Reviews · doi:10.1186/s13643-016-0384-4 · Cited by 26,092 · see citing works
Aerosol and surface stability of SARS-CoV-2 as compared with SARS-CoV-1
van Doremalen, N., Bushmaker, T., Morris, D. H., Holbrook, M. G., Gamble, A., Williamson, B. N., Tamin, A., Harcourt, J. L., Thornburg, N. J., Gerber, S. I., et al. (2020) · New England Journal of Medicine · doi:10.1056/nejmc2004973 · Cited by 9,951 · see citing works
KLEPEIS, N. E., NELSON, W. C., OTT, W. R., ROBINSON, J. P., TSANG, A. M., SWITZER, P., BEHAR, J. V., HERN, S. C., & ENGELMANN, W. H. (2001) · Journal of Exposure Science & Environmental Epidemiology · doi:10.1038/sj.jea.7500165 · Cited by 4,803 · see citing works
The Disproportionate Impact of COVID-19 on Racial and Ethnic Minorities in the United States
Tai, D. B. G., Shah, A., Doubeni, C. A., Sia, I. G., & Wieland, M. L. (2020) · Clinical Infectious Diseases · doi:10.1093/cid/ciaa815 · Cited by 1,390 · see citing works
Seasonality of Respiratory Viral Infections
Moriyama, M., Hugentobler, W., & Iwasaki, A. (2020) · Annual Review of Virology · doi:10.1146/annurev-virology-012420-022445 · Cited by 1,281 · see citing works
Urban Green Space and Its Impact on Human Health
Kondo, M., Fluehr, J., McKeon, T., & Branas, C. (2018) · International Journal of Environmental Research and Public Health · doi:10.3390/ijerph15030445 · Cited by 1,187 · see citing works
COVID-19 Outbreak Associated with Air Conditioning in Restaurant, Guangzhou, China, 2020
Lu, J., Gu, J., Li, K., Xu, C., Su, W., Lai, Z., DeQian, Z., Yu, C., Xu, B., & Yang, Z. (2020) · Emerging infectious diseases · doi:10.3201/eid2607.200764 · Cited by 880 · see citing works
Hamner, L., Dubbel, P., Capron, I., Ross, A., Jordan, A., Lee, J., Lynn, J., Ball, A., Narwal, S., Russell, S., et al. (2020) · MMWR Morbidity and Mortality Weekly Report · doi:10.15585/mmwr.mm6919e6 · Cited by 633 · see citing works
Indoor transmission of SARS‐CoV‐2
Qian, H., Miao, T., Liu, L., Zheng, X., Luo, D., & Li, Y. (2020) · Indoor Air · doi:10.1111/ina.12766 · Cited by 549 · see citing works
Airborne spread of infectious agents in the indoor environment
Wei, J., & Li, Y. (2016) · American Journal of Infection Control · doi:10.1016/j.ajic.2016.06.003 · Cited by 515 · see citing works
Jing, Q.-L., Liu, M.-J., Zhang, Z.-B., Fang, L.-Q., Yuan, J., Zhang, A.-R., Dean, N. E., Luo, L., Ma, M.-M., Longini, I. M., et al. (2020) · The Lancet Infectious Diseases · doi:10.1016/s1473-3099(20)30471-0 · Cited by 492 · see citing works
Coronavirus Disease Outbreak in Call Center, South Korea
Park, S. Y., Kim, Y., Yi, S., Lee, S., Na, B.-J., Kim, C. B., Kim, J.-I., Kim, H. S., Kim, Y. B., Park, Y., et al. (2020) · Emerging infectious diseases · doi:10.3201/eid2608.201274 · Cited by 468 · see citing works
What settings have been linked to SARS-CoV-2 transmission clusters?
Leclerc, Q. J., Fuller, N. M., Knight, L. E., CMMID COVID-19 Working Group, Funk, S., & Knight, G. M. (2020) · Wellcome Open Research · doi:10.12688/wellcomeopenres.15889.2 · Cited by 334 · see citing works
Closed environments facilitate secondary transmission of coronavirus disease 2019 (COVID-19)Preprint
Nishiura, H., Oshitani, H., Kobayashi, T., Saito, T., Sunagawa, T., Matsui, T., Wakita, T., MHLW COVID-19 Response Team, & Suzuki, M. (2020) · medRxiv · doi:10.1101/2020.02.28.20029272 · Cited by 333 · see citing works
Work-related COVID-19 transmission in six Asian countries/areas: A follow-up study
Lan, F., Wei, C.-F., Hsu, Y., Christiani, D. C., & Kales, S. N. (2020) · PLoS ONE · doi:10.1371/journal.pone.0233588 · Cited by 270 · see citing works
Hu, M., Lin, H., Wang, J., Xu, C., Tatem, A. J., Meng, B., Zhang, X., Liu, Y., Wang, P., Wu, G., et al. (2020) · Clinical Infectious Diseases · doi:10.1093/cid/ciaa1057 · Cited by 247 · see citing works
Facial Masking for Covid-19 — Potential for “Variolation” as We Await a Vaccine
Gandhi, M., & Rutherford, G. W. (2020) · New England Journal of Medicine · doi:10.1056/nejmp2026913 · Cited by 220 · see citing works
Self-citationSARS-CoV-2 Transmission and Infection Among Attendees of an Overnight Camp — Georgia, June 2020
Szablewski, C. M., Chang, K. T., Brown, M. M., Chu, V. T., Yousaf, A. R., Anyalechi, N., Aryee, P. A., Kirking, H. L., Lumsden, M., Mayweather, E., et al. (2020) · MMWR. Morbidity and Mortality Weekly Report · doi:10.15585/mmwr.mm6931e1 · Cited by 214 · see citing works
High COVID-19 Attack Rate Among Attendees at Events at a Church — Arkansas, March 2020
James, A. E., Eagle, L., Phillips, C., et al. (2020) · MMWR Morbidity and Mortality Weekly Report · doi:10.15585/mmwr.mm6920e2 · Cited by 154 · see citing works
Europe PMC: a full-text literature database for the life sciences and platform for innovation
The Europe PMC Consortium (2014) · Nucleic Acids Research · doi:10.1093/nar/gku1061 · Cited by 145 · see citing works
D’Angelo, L. J., Hierholzer, J. C., Keenlyside, R. A., et al. (1979) · The Journal of Infectious Diseases · doi:10.1093/infdis/140.1.42 · Cited by 111 · see citing works
Klompmaker, J. O., Hart, J. E., Holland, I., Sabath, M. B., Wu, X., Laden, F., Dominici, F., & James, P. (2020) · Environmental Research · doi:10.1016/j.envres.2021.111331 · Cited by 103 · see citing works
Black Lives Matter Protests, Social Distancing, and COVID-19Preprint
Dave, D., Friedson, A., Matsuzawa, K., et al. (2020) · SSRN Electronic Journal · doi:10.2139/ssrn.3631599 · Cited by 100 · see citing works
Willem, L., Kerckhove, K. V., Chao, D. L., Hens, N., & Beutels, P. (2012) · PLoS ONE · doi:10.1371/journal.pone.0048695 · Cited by 96 · see citing works
de Man, P., Paltansing, S., Ong, D. S. Y., Vaessen, N., van Nielen, G., & Koeleman, J. G. M. (2020) · Clinical Infectious Diseases · doi:10.1093/cid/ciaa1270 · Cited by 72 · see citing works
Outbreaks associated to large open air festivals, including music festivals, 1980 to 2012
Botelho-Nevers, É., & Gautret, P. (2013) · Eurosurveillance · doi:10.2807/ese.18.11.20426-en · Cited by 66 · see citing works
Mortality Risk Factors for Pandemic Influenza on New Zealand Troop Ship, 1918
Summers, J. A., Wilson, N., Baker, M. G., & Shanks, G. D. (2010) · Emerging infectious diseases · doi:10.3201/eid1612.100429 · Cited by 34 · see citing works
Rainey, J. J., Phelps, T., & Shi, J. (2016) · PLoS ONE · doi:10.1371/journal.pone.0160378 · Cited by 30 · see citing works
Relationship of George Floyd protests to increases in COVID-19 cases using event study methodology
Valentine, R., Valentine, D. B., & Valentine, J. L. (2020) · Journal of Public Health · doi:10.1093/pubmed/fdaa127 · Cited by 29 · see citing works
Transmission by super-spreading event of pandemic A/H1N1 2009 influenza during road and train travel
Pestre, V., Morel, B., Encrenaz, N., Gagneux‐Brunon, A., Lucht, F., Pozzetto, B., & Berthelot, P. (2011) · Scandinavian Journal of Infectious Diseases · doi:10.3109/00365548.2011.631936 · Cited by 24 · see citing works
Public Lands Are Essential to Public Health During a Pandemic
Razani, N., Radhakrishna, R., & Chan, C. (2020) · PEDIATRICS · doi:10.1542/peds.2020-1271 · Cited by 22 · see citing works
Self-citationCritical Illness Due to Covid-19: A Description of the Surge in a Single Center in Sioux Falls.
Jamous, F. G., Meyer, N., Buus, D., et al. (2020) · PubMed · Cited by 22 · see citing works
Will Coronavirus Disease 2019 Become Seasonal?
Kanzawa, M., Spindler, H., Anglemyer, A., et al. (2020) · Journal of Infectious Diseases · doi:10.1093/infdis/jiaa345 · Cited by 20 · see citing works
Associations between COVID-19 transmission rates, park use, and landscape structurePreprint
Johnson, T. F., Hordley, L. A., Greenwell, M. P., et al. (2020) · medRxiv · doi:10.1101/2020.10.20.20215731 · Cited by 12 · see citing works
Figueroa, A., Gulati, R. K., & Rainey, J. J. (2017) · PLoS ONE · doi:10.1371/journal.pone.0186730 · Cited by 11 · see citing works
Effect of park use and landscape structure on COVID-19 transmission rates
Johnson, T. D., Hordley, L. A., Greenwell, M. P., et al. (2021) · The Science of The Total Environment · Cited by 7 · see citing works
Miron, O., Yu, K., Wilf‐Miron, R., et al. (2020) · medRxiv · doi:10.1101/2020.10.22.20184630 · Cited by 6 · see citing works
Flagged first, then by citations
Research works printed but not linked: 1
- Blocken B, Malizia F, Druenen T Van, Marchal T. Towards aer- odynamically equivalent COVID-19 1.5 m social distancing for walking and running [Preprint]. 2020. Available at: http://www.urbanphysics.net/Social%20Distancing%20 v20_White_Paper.pdf ?fbclid=IwAR05zYIcuHQnDEr_ jEsrsHBFiNYoDa4Fw3CKAWwHFANgnZ-ug5dxrNpsLS8. Accessed 28 December 2020.
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Greenhalgh, T., Jimenez, J. L., Prather, K. A., Tufekci, Z., Fisman, D., & Schooley, R. (2021) · The Lancet · doi:10.1016/s0140-6736(21)00869-2 · Cited by 930 · see citing works
The Lancet Commission on lessons for the future from the COVID-19 pandemic
Sachs, J. D., Karim, S. S. A., Aknin, L., Allen, J., Brosbøl, K., Colombo, F., Barron, G. C., Espinosa, M. F., Gaspar, V., Gaviria, A., et al. (2022) · The Lancet · doi:10.1016/s0140-6736(22)01585-9 · Cited by 842 · see citing works
Long distance airborne transmission of SARS-CoV-2: rapid systematic review
Duval, D., Palmer, J. C., Tudge, I., Pearce-Smith, N., O’Connell, E., Bennett, A., & Clark, R. (2022) · BMJ · doi:10.1136/bmj-2021-068743 · Cited by 120 · see citing works
Indoor Aerosol Science Aspects of SARS-CoV-2 Transmission
Nazaroff, W. W. (2022) · Indoor Air · doi:10.1111/ina.12970 · Cited by 70 · see citing works
Purity, Danger, and Patriotism: The Struggle for a Veteran Home during the COVID-19 Pandemic
Kalofonos, I., & McCoy, M. (2023) · Pathogens · doi:10.3390/pathogens12030482 · Cited by 2 · see citing works
- Authors
- Bulfone, T. C., Malekinejad, M., Rutherford, G. W., & Razani, N.
- Affiliations
- University of California, San Francisco (US)
- Corresponding author
- Razani, Nooshin
- Venue
- The Journal of Infectious Diseases
- Publisher
- Oxford University Press (OUP)
- Published
- 2020-11-29
- Volume
- 223
- Issue
- 4
- Pages
- 550-561
- ISSN
- 0022-1899 (ISSN-L)
- 1537-6613
- PMC
- PMC7798940
- OpenAlex
- W3108113884
- Cited by
- 355
- References
- 38
- Citations by year
- 2026: 11 · 2025: 25 · 2024: 45 · 2023: 74 · 2022: 114 · 2021: 85 · 2020: 1
- FWCI
- 9.60
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Licence
- academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model (vor)
- Locations
- The Journal of Infectious Diseases (publishedVersion)
- Europe PMC (PubMed Central) (publishedVersion)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- Funders
- University of California Berkeley
- University of California, San Francisco
- Topics
- Health Sciences › Medicine › Pulmonary and Respiratory Medicine › Infection Control and Ventilation
- Physical Sciences › Mathematics › Modeling and Simulation › COVID-19 epidemiological studies
- Health Sciences › Medicine › Infectious Diseases › SARS-CoV-2 and COVID-19 Research
- Keywords
- SARS-CoV-2, outdoor transmission, indoor transmission, respiratory viruses, influenza, adenovirus, transmission risk factors, personal protective equipment, COVID-19 pandemic
- MeSH terms
- COVID-19, SARS-CoV-2, Environmental Exposure, Humans, Risk Factors, Disease Transmission, Infectious
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