Does Lockdown Decrease the Protective Role of Ultraviolet-B (UVB) Radiation in Reducing COVID-19 Deaths?

Abstract

<jats:p>Background: Nations are imposing unprecedented measures at large-scale to contain the spread of COVID-19 pandemic. Recent studies indicate that measures such as lockdowns may have slowed down the growth of COVID-19. However, in addition to substantial economic and social costs, these measures also limit the exposure to Ultraviolet-B radiation (UVB). Emerging observational evidence indicate the protective role of UVB and vitamin D in reducing the severity and mortality of COVID-19 deaths. In this observational study, we empirically outline the independent protective roles of lockdown and UVB exposure as measured by ultraviolet index (UVI), whilst also examining whether the severity of lockdown is associated with a reduction in the protective role. Methods. We apply a log-linear fixed-effects model to a panel dataset of 162 countries over a period of 108 days (n=6049). We use the cumulative number of COVID-19 deaths as the dependent variable and isolate the mitigating influence of lockdown severity on the association between UVI and growth-rates of COVID-19 deaths from time-constant country-specific and time-varying country-specific potentially confounding factors. Findings: After controlling for time-constant and time-varying factors, we find that a unit increase in UVI and lockdown severity are independently associated with 17% [-1.8 percentage points] and 77% [-7.9 percentage points] decline in COVID-19 deaths growth rate, indicating their respective protective roles. However, the widely utilized and least severe lockdown (recommendation to not leave the house) already fully mitigates the protective role of UVI by 95% [1.8 percentage points] indicating its downside. Interpretation: We find that lockdown severity and UVI are independently associated with a slowdown in the daily growth rates of cumulative COVID-19 deaths. However, we find consistent evidence that increase in lockdown severity is associated with a significant reduction in the protective role of UVI in reducing COVID-19 deaths. Our results suggest that lockdowns in conjunction with adequate exposure to UVB radiation might have provided even more substantial health benefits, than lockdowns alone. For example, we estimate that there would be 21% fewer deaths on average with sufficient UVB exposure while people were recommended not to leave their house. Therefore, our study outlines the importance of considering UVB exposure, especially while implementing lockdowns and may support policy decision making in countries imposing such measures. </jats:p>

Investigating the Potential for Ultraviolet Light to Modulate Morbidity and Mortality From COVID-19: A Narrative Review and Update

“…The strength of these orders and their implementation by governments has varied significantly around world. In a preprint mathematical modeling study, done across 162 countries, every "unit increase" in lockdown severity associated with a 77% decline in COVID-19 growth rates (64). The impacts of lockdown measures on sun exposure levels are largely undescribed, although depending on their severity are likely to be significant.…”

Role of Weather Factors in COVID-19 Deaths in Tropical Climate: A Data-Driven Study Focused on Brazil Manuscript

“…UV index measures the intensity of UV radiation and is used as a warning for sunburn risk, mostly by solar UVB radiation spectrum 290-315 nm 32 , the spectrum which helps in vitamin D skin synthesis 33 . Early studies show a protective role of UVB and vitamin D in COVID-19 34,35,36,37,38 . 1,25-dihydroxyvitamin D [1,25 (OH) 2 D], an active vitamin D form, plays an essential role in modulating innate and adaptive immune systems 39,40 , renin-angiotensin system (RAS) 40–42 as well as in modulating the inflammatory response 39,40 .…”

“…Furthermore, humans can store vitamin D produced via the UV Index to be used later 34 . According to prior studies, time-constant factors such as population, genetic profile, culture, density, age structure, gender, underlying disease, co-morbidities, skin pigmentation, gender, mobility, underlying conditions, diet or socio-economic factors are relevant to consider in COVID-19 34,35,47 . As COVID-19 is a novel disease, we anticipate that controlling for other weather factors such as dew point, pressure, wind speed, and wind gust may increase the robustness of the conclusions.…”

“…Although COVID-19 studies indicate that these relevant weather factors may influence COVID-19 cases as well as deaths, the magnitude and direction of those associations remain inconclusive. Results of some studies a indicate that COVID-19 spread and plausibly deaths associate negatively with temperature 10,15,47,49–51 , humidity 10,15,52,53 , UV Index 34,35 , precipitation 48,54 , ozone 20 . However, the results of other studies indicate no association with temperature 55,56 , humidity 56 ,precipitation 50 , UV radiation 57 .…”

Implications of Monsoon Season & UVB Radiation for COVID-19 in India Manuscript

“…Recent observational and clinical studies show that vitamin D deficiency might be linked to incidence 2,3 , severity 4 5 and mortality [6][7][8] associated with COVID-19. Recent studies show that vitamin D and its primary source Ultraviolet-B radiation (UVB) may play a protective role in mitigating COVID-19 deaths 9,10 . Studies indicate that south-west monsoon season (monsoon season) plays a role in the dynamics of contagious diseases, which tend to peak post-monsoon season 11 .…”