A delayed modulation of solar ultraviolet radiation on the COVID-19 transmission reflects an incubation period

Abstract

Laboratory experiments have revealed the meteorological sensitivity of the virus of the coronavirus disease 2019 (COVID-19). However, no consensus has been reached about how the meteorological conditions modulate the virus transmission as it is constrained more often by non-meteorological factors. Here, we find that the non-meteorological factors constrain statistically-least the growth rate of cumulative confirmed cases in a country when the cases arrive around 2500-3000. The least-constrained growth rate correlates with the near-surface ultraviolet flux and temperature significantly (correlation coefficients r=-0.55±0.08 and -0.45±0.08 at p 10-5, respectively). In response to increases of 1W/m2 ultraviolet and 1°C temperature, the growth rate decreases by 0.33±.11% and 0.18±.08% per day, respectively. The response to the ultraviolet flux exhibits a delay by about 7 days, providing an independent measure of the incubation period. Our quantifications imply a seasonality of COVID-19 and a high risk of a pandemic resurgence in the upcoming boreal winter, suggesting a need for seasonal adaption in public policies.