Sunlight linked with lower Covid-19 deaths, study suggests

Increased exposure to sunlight has been linked to a lower risk of dying from Covid-19, an observational study has suggested.

People living in sunnier areas, with the highest level of exposure to UVA rays, are associated with fewer deaths from coronavirus compared with those with lower levels, experts from the University of Edinburgh said.

The study compared all recorded deaths from Covid-19 in the continental US from January to April 2020 with UV levels for 2,474 US counties for the same time period.

Researchers said they found the same results when they repeated the analysis in England and Italy.

Factors known to be associated with increased exposure to Covid-19 and risk of death - including age, ethnicity, socioeconomic status, population density, air pollution, temperature and infection levels in local areas - were taken into account during the observational study.

There have been some observational studies that suggest vitamin D, which is produced in the skin in response to sunlight, has some usefulness in preventing Covid-19.

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However, researchers at the University of Edinburgh said the observed reduction in risk of death from the disease could not be explained by higher levels of vitamin D.

Only areas with insufficient levels of UVB to produce significant vitamin D in the body were included in the study, which was published in the British Journal of Dermatology.

One suggestion to explain the lower number of deaths is that sunlight exposure prompts the skin to release nitric oxide, which could reduce the ability of Sars-CoV-2 to replicate, as has been found in some lab studies.

The same group of researchers previously found that increased sunlight exposure is linked to better cardiovascular health, with lower blood pressure and fewer heart attacks. Heart disease is a known risk factor in dying from coronavirus, which could explain the latest findings, they said.

Due to the observational nature of the study, the team said it was not possible to establish cause and effect, but hoped it could lead to interventions that could be tested as potential treatments.

Dr Richard Weller, co-author of the study, consultant dermatologist and Reader at the University of Edinburgh, said: “There is still so much we don’t understand about Covid-19, which has resulted in so many deaths worldwide. These early results open up sunlight exposure as one way of potentially reducing the risk of death.”

Professor Chris Dibben, chair in Health Geography at the University of Edinburgh and co-author said: “The relationship between Covid-19 mortality, season and latitude has been quite striking, here we offer an alternative explanation for this phenomenon.”