Guest post by Jim Steele

I want to encourage people to go outside and get some sunshine. If walks in the park are outlawed, then limited sunbathing in your back yard, or apartment roof tops would help. I don’t give medical advice, but this is a no-brainer, no-regrets suggestion.

Scientists have long investigated why the flu season dramatically ends in the warmer months. One key factor is our immune systems improve when sun shining on our skin produces the all-important Vitamin D. It is a form of vitamin D that is more effective than what is added to our milk.

Researchers reported, “vitamin D deficiency is common in the winter, and activated vitamin D, a steroid hormone, has profound effects on human immunity. D acts as an immune system modulator, preventing excessive expression of inflammatory cytokines and increasing the ‘oxidative burst’ potential of macrophages. Perhaps most importantly, it dramatically stimulates the expression of potent anti-microbial peptides, which exist in neutrophils, monocytes, natural killer cells, and in epithelial cells lining the respiratory tract where they play a major role in protecting the lung from infection. Volunteers inoculated with live attenuated influenza virus are more likely to develop fever and serological evidence of an immune response in the winter. Vitamin D deficiency predisposes children to respiratory infections.

If we do not get enough sunshine, sheltering in place just might have the unintended consequence of prolonging the COVID 19 epidemic. As the elderly become less mobile and spend less time outside, a vitamin D deficiency would only amplify their vulnerability.

April is the time flu infections dramatically fall. Of course, the COVID 19 virus differs from influenza, but our immune system’s ability to fight all viruses is key. Maybe a little April sunshine will minimize the COVID 19 spread and flatten the curve.

Jim Steele is Director emeritus of San Francisco State’s Sierra Nevada Field Campus and authored Landscapes and Cycles: An Environmentalist’s Journey to Climate Skepticism