Tommaso Celeste Bulfone1, Mohsen Malekinejad2, George W Rutherford2,3, Nooshin Razani2,3. 1. Joint Medical Program, University of California Berkeley-University of California San Francisco, Berkeley, California, USA. 2. Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, California, USA. 3. Department of Pediatrics, University of California San Francisco, San Francisco, California, USA.
Abstract
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.
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.
Authors: Kevin Escandón; Angela L Rasmussen; Isaac I Bogoch; Eleanor J Murray; Karina Escandón; Saskia V Popescu; Jason Kindrachuk Journal: BMC Infect Dis Date: 2021-07-27 Impact factor: 3.090
Authors: Andria Mousa; Peter Winskill; Oliver J Watson; Oliver Ratmann; Mélodie Monod; Marco Ajelli; Aldiouma Diallo; Peter J Dodd; Carlos G Grijalva; Moses Chapa Kiti; Anand Krishnan; Rakesh Kumar; Supriya Kumar; Kin On Kwok; Claudio F Lanata; Olivier Le Polain de Waroux; Kathy Leung; Wiriya Mahikul; Alessia Melegaro; Carl D Morrow; Joël Mossong; Eleanor Fg Neal; David J Nokes; Wirichada Pan-Ngum; Gail E Potter; Fiona M Russell; Siddhartha Saha; Jonathan D Sugimoto; Wan In Wei; Robin R Wood; Joseph T Wu; Juanjuan Zhang; Patrick Gt Walker; Charles Whittaker Journal: medRxiv Date: 2021-06-15