Pete, thanks for the article on Vitamin D3 and elderberry.
We have used both successfully for flu. Knocked it out in two days.
If Nonnie said the Elderberry works for flu it probably does.
In this case an Isreali Virologist investigated it and developed a syrup from it. You can probably buy it at a drugstore. I think That NatureWay Sambacol has the higest amount of active ingrediant. (5 grams per 2 teaspoons.) I mix it with grapejuice and have it at breakfast.
It does not kill the flu virus. It works by inhibiting its ability to replicate.