Role of meteorological factors in the transmission of SARS-CoV-2 in the United States

Abstract

BACKGROUND AND AIM: Improved understanding of the effects of meteorological conditions on the transmission of SARS-CoV-2, the causative agent for COVID-19 disease, is urgently needed to inform mitigation efforts. Here, we estimated the relationship between air temperature, specific humidity (SH), and ultraviolet (UV) radiation and SARS-CoV-2 transmission in 2,669 U.S. counties with abundant reported cases from March 15 to December 31, 2020. METHODS: Daily air temperature and SH data were extracted from the North America Land Data Assimilation System project, and daily UV radiation data were extracted from the European Centre for Medium-Range Weather Forecasts ERA5 climate reanalysis. County-level daily effective reproductive numbers ({Rt}) were estimated using a dynamic metapopulation model informed by human mobility data. We applied a distributed lag non-linear model combined with generalized additive models to estimate the associations of short-term meteorological conditions with {Rt} and the attributable fractions, adjusting for spatiotemporal variations in {Rt} and potential confounders. RESULTS:Preliminary analyses showed that lower air temperature (from 20 to 40 °C), lower SH, and lower UV radiation were significantly associated with increased {Rt}. The fraction of {Rt} attributable to temperature, SH, and UV radiation were 3.73% (95% eCI: 3.66 - 3.76%), 9.35% (95% eCI: 9.27 - 9.39%), and 4.44% (95% eCI: 4.38 - 4.47%), respectively. In total, meteorological factors contributed to approximately 18% of {Rt}. The fractions attributable to meteorological factors generally were higher in northern counties than in southern counties. CONCLUSIONS:Our findings indicate that cold and dry weather and low amount of UV radiation are moderately associated with increased SARS-CoV-2 transmissibility, with humidity playing the largest role. KEYWORDS: COVID-19,Temperature,Climate,Infectious diseases