I read an article a few years ago that postulated that Vitamin D itself (whatever it is) was only part of the Vitamin D story. Essentially, sunlight confers benefits that are associated with Vitamin D, but Vitamin D itself may not be the cause of those benefits. And so, supplements are not sufficient. Does anyone know enough to comment on that generally, and regarding COVID?

Edit: here is the article https://www.outsideonline.com/2380751/sunscreen-sun-exposure...