Bulfone TC, Malekinejad M, Rutherford GW, et al. - Researchers sought to report on SARS-CoV-2 transmission in outdoor compared with indoor settings. They systematically reviewed peer-reviewed papers indexed in PubMed, EMBASE and Web of Science and pre-prints in Europe PMC through August 12, 2020. They identified five studies suggesting an occurrence of a low proportion of reported global SARS-CoV-2 infections outdoors (< 10%) and the very high odds of indoor transmission compared with outdoors (18.7 times). Influenza transmission outdoors was described in five studies and adenovirus transmission outdoors was described in two studies. Evidence gained thereby provides support to the wide-held belief that the risk of SARS-CoV-2 transmission is lower outdoors.