Slower COVID-19 Morbidity and Mortality Growth at Higher Solar Irradiance and Elevation

Abstract

The effect of temperature and irradiance on COVID-19 will determine the course of the pandemic as the seasons change. We show case and death counts had significantly lower growth rates at higher temperatures (>14 °C) when aligned for stage in the epidemic. We then show irradiance and in particular solar elevation angle in combination with cloudopacity explain COVID-19 morbidity and mortality growth better than temperature: a reduction of mean solar elevation of 9 degrees led on average to a 2500% increase in COVID-19 case growth over the following two weeks. COVID-19 exploded during the darkest January in Wuhan in over a decade. Our results suggest transmission models should incorporate solar elevation and that the impact of UV irradiance on individual morbidity and mortality should be tested. We discuss implications for the best locations and optimal behaviors for high-risk individuals to weather the pandemic.

Note:

Funding: None to declare

Conflict of Interest: No competing interests to declare.

Keywords: irradiance, COVID-19, coronavirus, SARS-CoV-2, sunlight, vitamin D, UV