So how might extra sunlight curb COVID-19?
According to Weller’s group, one possible explanation is that sun exposure causes the skin to release a chemical called nitric oxide. Some laboratory studies have found that nitric oxide may reduce the ability of the new coronavirus to replicate and spread. The study authors are planning to follow-up with more research regarding this theory.
Previous research by the same team found that increased sunlight exposure is associated with better heart health, lower blood pressure and fewer heart attacks. Heart disease is a known risk factor in dying from COVID-19, so that past research could also help explain the new findings, they suggested.
Two COVID-19 experts in the United States agreed that the findings were intriguing, but merited more study.
“The research does not establish a cause and effect, and represents an association at best,” stressed Dr. Robert Glatter, an emergency medicine physician at Lenox Hill Hospital in New York City. He wasn’t surprised that vitamin D wasn’t credited with any health benefit.
“While there is evidence that vitamin D may have beneficial effects on immune function, a specific antiviral effect remains unproven at this time,” Glatter said. “In fact, a randomized controlled study of people with moderate to severe COVID-19 who received high-dose vitamin D demonstrated no benefit.”
Dr. Amesh Adalja, senior scholar at the Johns Hopkins Center for Health Security, in Baltimore, is an expert on viruses. He said the research raises interesting questions, but the nitric oxide hypothesis needs more study.
“Putting that link together to show the mechanism of how this is happening, I think that’s where you’d want to see this line of research go, in order to show that there’s also a vitamin D-independent benefit of sunlight,” Adalja said.
The U.S. Centers for Disease Control and Prevention has more on COVID-19 prevention.
SOURCES: Amesh Adalja, MD, senior scholar, Center for Health Security, Johns Hopkins Bloomberg School of Public Health, Baltimore; Robert Glatter, MD, emergency medicine physician, Lenox Hill Hospital, New York City; British Journal of Dermatology, April 8, 2021;University of Edinburgh, news release, April 8, 2021