Socioeconomic Restrictions Slowdown COVID-19 Far More Effectively than Favorable Weather: Satellite Reveals How Much the World Has Done

Background: Countries initiate public health measures to slow the COVID-19 transmission, from stringent quarantines including city lockdown, to simply recommendations of social distancing, differentiated efforts for the similar purpose of restricting social activities (SA). None has quantified the impact of restricting SA on the COVID-19 spread, in the context of weather conditions.Method: This study models the impact of restricting SA on the transmissivity of the COVID-19 all over the world by building a global panel regression model using 3,315,748 confirmed infectees by April 17. We use satellite readings of Nitrogen Dioxide (NO2), a pollutant emitted from socioeconomic activities, to proxy the level of SA, and discuss the implications under the influences of weather. We quantify additional nonpharmaceutica measures, and regional medical facility capacity through region-by time fixed effects (RTFE).Findings: We find that restricting SA has a leading contribution to lowering the reproductive number by 18.3% (95% Confidence Interval [CI] 14.8%-21.8%), while weather conditions including ultraviolet, relative humidity, and wind contribute a less amount. Temperature has a non-monotonic impact on the transmission. In developed countries and China, the SA effect is more pronounced whereas the weather effect is downplayed. Until April 17, the number of spared infectees due to restricting SA are estimated to be 40,964 (95% CI 31,463-51,470), 180,336 (95% CI 142,860-219,445), and 174,494 (95% CI 139,202-210,841), in China, United States, and Europe respectively. Regions except for China, Australia (including New Zealand), and south Korea see a steep upward trend of spared infectees due to restricting SA with US and Europe show far steeper trends. RTFE shows a rapid increased impact on reducing the transmissivity in all regions except for Africa and Latin America.Interpretation: In China and developed countries, the pronounced contribution of SA restriction and weakened explaining variables about weather might be explained by people’s tendency to stay indoors most of the time, indicating the limitation of relying on favorable weather to stop the virus transmission. Although we suspect that the virus has a viable temperature range, we need more data in warmer seasons to confirm the hypothesis. The analyses of the trend of spared infectees suggests that the pandemic might be under control in China, South Korea, Australia, and that other countries might see greater risks of reopening the economy too soon. RTFE analyses raise concerns over medical fundamental infrastructure’s ability to control the pandemic in Africa and Latin America.Funding Statement: XS. received funding support from Eversource Energy Center at the University of Connecticut, CC received funding from China Scholarship Council, HL receives PhD fellowship from the Finance Department at the University of Connecticut.Declaration of Interests: Authors declare no competing interests.