I believe that the very large consensus of opinion, both scientific and otherwise, is that Vitamin D is both immunomodulatory as well as immune boosting. The two are not mutually exclusive, as we see with magnesium, curcumin, oleander and blackseed oil - all of which are immune modulators as well as immune stimulators, and all of which I highly recommend to people who have immune disorders where the immune system turns back on the body.