Evidence of Protective Role of Ultraviolet-B (UVB) Radiation in Reducing COVID-19 Deaths
42 Pages Posted: 1 May 2020 Last revised: 12 May 2020
Date Written: April 01, 2020
Background: Research is ongoing to identify an effective way to prevent or treat COVID-19, but
thus far these efforts have not yet identified a possible solution. Prior studies indicate the
protective role of Ultraviolet-B (UVB) radiation in human health, mediated by vitamin D
synthesis. In this study, we empirically outline a negative association of UVB radiation as
measured by ultraviolet index (UVI) with the number of deaths attributed to COVID-19 (COVID-
Methods: We carry out an observational study, applying a fixed-effect log-linear regression model
to a panel dataset of 152 countries over a period of 108 days (n=6524). We use the cumulative
number of COVID-19 deaths and case-fatality rate (CFR) as the main dependent variables to test
our hypothesis and isolate UVI effect from potential confounding factors such as underlying time
trends, country-specific time-constant and time-varying factors such as weather.
Findings: After controlling for time-constant and time-varying factors, we find that a permanent
unit increase in UVI is associated with a 1.2 percentage points decline in daily growth rates of
cumulative COVID-19 deaths [p < 0.01] as well as a 1.0 percentage points decline in the daily
growth rates of CFR [p < 0.05]. These results represent a significant percentage reduction in terms
of the daily growth rates of cumulative COVID-19 deaths (-11.88%) and CFR (-38.46%). Our
results are consistent across different model specifications.
Interpretation: We find a significant negative association between UVI and COVID-19 deaths,
indicating evidence of the protective role of UVB in mitigating COVID-19 deaths. If confirmed
via clinical studies, then the possibility of mitigating COVID-19 deaths via sensible sunlight
exposure or vitamin D intervention will be very attractive because it is cost-effective and widely
Note: Funding: This study is not sponsored by any organization.
Conflict of Interest: RKM is a part-time PhD student at Goethe University, Frankfurt. He also is a full-time employee of a multinational chemical company involved in vitamin D business and holds the shares of the company. This study is intended to contribute to the ongoing COVID-19 crisis and is not sponsored by his company. BS also holds shares of the company. All other authors declare no competing interests.
Keywords: COVID-19; Coronavirus; UVB Radiation; UV Index; Ultraviolet; Sunlight; Vitamin D; Vitamin D deficiency; Vitamin D COVID-19; COVID-19 Clinical outcome; Infectious disease; Public health; COVID-19 Clinical Trial; Mortality
JEL Classification: I1,I10, I12, I18, I28, J1, I18
Suggested Citation: Suggested Citation