Solar areas are associated with fewer deaths than Covid-19, observational research suggests.
Increased sun exposure – especially UVA – could act as a simple public health intervention if further research finds it causes a reduction in the death rate, experts say.
Researchers from the University of Edinburgh compared all recorded deaths from Covid-19 in the continental United States from January to April 2020 with UV levels for 2,474 U.S. counties over the same time period.
The study found that people living in areas with the highest levels of UVA exposure – which makes up 95 percent of the sun’s UV light – have a lower risk of death from Covid-19 compared to those with lower levels. The analysis was repeated in England and Italy with the same results.
The researchers took into account factors known to be associated with increased virus exposure and risk of death, such as age, ethnicity, socioeconomic status, population density, air pollution, temperature and level of infection in local areas.
The observed reduction in the risk of death from Covid-19 cannot be explained by higher levels of vitamin D, experts said. Only areas with insufficient UVB levels to produce significant vitamin D in the body were included in the study.
One of the explanations for the lower number of deaths, which researchers are monitoring, is that exposure to sunlight causes the skin to release nitric oxide. This may reduce the replication ability of SARS Coronavirus2 – the causative agent of Covid-19 – as found in some laboratory studies.
Previous research from the same group has shown that increased exposure to sunlight is associated with improved cardiovascular health, with lower blood pressure and fewer heart attacks. As heart disease is a known risk factor for dying from Covid-19, this could explain the latest findings.
The team says that due to the observational nature of the study, it is not possible to determine the cause and effect. However, this can lead to interventions that could be tested as potential treatments.
The paper was published in British Journal of Dermatology, official publication of the British Association of Dermatologists: https: /
Dr Richard Weller, correspondent, consultant dermatologist and reader at the University of Edinburgh, said: “We still don’t understand so much about Covid-19, which has resulted in so many deaths worldwide. These early results open up sunlight exposure as one of ways to potentially reduce the risk of death. “
Professor Chris Dibben, chairman of health geography at the University of Edinburgh and co-author, said: “The mortality ratio of Covid-19, season and latitude was quite striking, here we offer an alternative explanation for this phenomenon.”
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