Thought this was interesting and of possible value:

Former CDC Chief Dr. Tom Frieden: Coronavirus infection risk may be reduced by Vitamin D

"Vitamin D supplementation reduces the risk of respiratory infection, regulates cytokine production and can limit the risk of other viruses such as influenza. A respiratory infection can result in cytokine storms – a vicious cycle in which our inflammatory cells damage organs throughout the body – which increase mortality for those with COVID-19. Adequate Vitamin D may potentially provide some modest protection for vulnerable populations.

This is especially important for people who are Vitamin D deficient – and, surprisingly, that might include more than 40 percent of US adults. People who live in the northern part of the U.S. are at greater risk of deficiency.

There is evidence of seasonality in some respiratory illnesses, including influenza and tuberculosis. A leading hypothesis is that seasonality is due to the reduction in Vitamin D because of decreased exposure to sunlight in winter months. There is no seasonality of influenza or tuberculosis in some tropical climates (such as south India), where weather – and sunlight exposure – remains more constant throughout the year."

Cont:

https://www.foxnews.com/opinion/form...with-vitamin-d