How Sunlight, the Immune System, and Covid-19 Interact

For thousands of years, humans have recognized that the sun plays a role in the emergence and transmission of viruses

Markham Heid
Elemental

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Illustration: Shuhua Xiong

Last month, during a now-infamous press conference, Donald Trump speculated about the ways in which sunlight and chemical disinfectants could help protect people from the threat of Covid-19. Trump seemed to suggest that injecting disinfectants could have some utility — a comment that drew immediate scrutiny and scorn.

Much less attention was paid to the president’s statement that sunlight might safeguard people from the virus. “Supposing we hit the body with a tremendous — whether it’s ultraviolet or just very powerful light,” Trump said. “Supposing you brought the light inside the body, which you can do either through the skin or in some other way.”

When it comes to potential Covid-19 treatments, the president’s speculations have been numerous and frequently misguided. But the idea that sunlight could counteract Covid-19, both inside and outside the body, is not all that far-fetched.

Richard Weller, MD, is a dermatologist and sunlight researcher at the University of Edinburgh in the U.K. Weller says he’s looked at Covid-19 data in the United States, and that there seems to be a…

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Markham Heid
Elemental

I’m a frequent contributor at TIME, the New York Times, and other media orgs. I write mostly about health and science. I like long walks and the Grateful Dead.