Short-term effects of weather parameters on COVID-19 morbidity in select US cities

Runkle, Jennifer D.; Sugg, Margaret M.; Leeper, Ronald D.; Rao, Yuhan; Mathews, Jessica L.; Rennie, Jared J.

Abstract Little is known about the environmental conditions that drive the spatiotemporal patterns of SARS-CoV-2, and preliminary research suggests an association with weather parameters. However, the relationship with temperature and humidity is not yet apparent for COVID-19 cases in US cities first impacted. The objective of this study is to evaluate the association between COVID-19 cases and weather parameters in select US cities. A case-crossover design with a distributed lag nonlinear model was used to evaluate the contribution of ambient temperature and specific humidity on COVID-19 cases in select US cities. The case-crossover examines each COVID case as its own control at different time periods (before and after transmission occurred). We modeled the effect of temperature and humidity on COVID-19 transmission using a lag period of 7 days. A subset of 8 cities were evaluated for the relationship with weather parameters and 5 cities were evaluated in detail. Short-term exposure to humidity was positively associated with COVID-19 transmission in 4 cities. The associations were small with ¾ cities exhibiting higher COVID19 transmission with specific humidity that ranged from 6 to 9 g/kg. Our results suggest that weather should be considered in infectious disease modeling efforts and future work is needed over a longer time period and across different locations to clearly establish the weather-COVID19 relationship.