JoAnn E. Manson, MD, DrPH
We've known for a long time that it's important to avoid vitamin D deficiency for bone health, cardiometabolic health, and other purposes. But it may be even more important now than ever. There's emerging and growing evidence that vitamin D status may be relevant to the risk of developing COVID-19 infection and to the severity of the disease.
Vitamin D is important to innate immunity and boosts immune function against viral diseases. We also know that vitamin D has an immune-modulating effect and can lower inflammation, and this may be relevant to the respiratory response during COVID-19 and the cytokine storm that's been demonstrated.
There are laboratory (cell-culture) studies of respiratory cells that document some of these effects of vitamin D. There's also evidence that patients with respiratory infections tend to have lower blood levels of 25-hydroxy-vitamin D.