Why they did this study is beyond me! Any informed physician/medical researcher knows (or should know) that it takes up to 2 weeks for Vitamin D3 to be converted to its more active form! High doses do nothing to speed up that conversion process. In those with liver and/or kidney disease it make take even longer. That essentially means that the results of this study were a forgone conclusion! There have been studies however that show that individuals who have taken Vitamin D3 on a casual basis have lower infection rate and studies that show that individuals whose Vitamin D3 levels are above 20 ng/ml generally have a milder course if infected than those whose levels are below that cutoff range.