Abstract for: Estimation of Weather Effect on SARS-CoV-2 Transmission: Methodological Considerations
Understanding how environmental factors impact SARS-CoV-2 transmission informs global containment efforts. Despite high scientific and public interest and multiple research reports, there is currently no consensus on the impact of environmental factors on SARS-CoV-2 transmission. To address this research gap, we conducted a multi-method study to examine the relative risk of the transmission due to weather and ambient air pollution. In this multi-method research, feedback-rich dynamic simulation models were used to test, improve, and validate our statistical methods. Then, we estimated the daily reproduction number at 3,739 global locations early in the pandemic. We found that several weather variables and ambient air pollution were associated with the spread of COVID-19. The results pointed to a moderate, negative relationship between the estimated reproduction number and temperatures above 25oC, a U-shaped relationship with outdoor ultraviolet exposure. Results are robust to multiple assumptions. Independent research building on our estimates provides strong support for the resulting projections across nations.