https://www.sciencedaily.com/releases/2020/05/200508083551.htm > "Our study provides important new evidence, using global data from the COVID-19 epidemic, that these public health interventions have reduced epidemic growth," says Dr. Peter Jüni, Institute for Health Policy, Management and Evaluation, University of Toronto, and St. Michael's Hospital, Toronto, Ontario. > The Canadian study looked at 144 geopolitical areas -- states and provinces in Australia, the United States and Canada as well as various countries around the world -- and a total of more than 375 600 confirmed COVID-19 cases. China, Italy, Iran and South Korea were excluded because the virus was either waning in the case of China or in full disease outbreak at the time of the analysis in others. To estimate epidemic growth, researchers compared the number of cases on March 27 with cases on March 20, 2020, and determined the influence of latitude, temperature, humidity, school closures, restrictions of mass gatherings and social distancing measured during the exposure period of March 7 to 13.