It's hard to take seriously a source that says:
- The mechanism of action of vitamin D in infection... suggests pharmaceutical doses of vitamin D (1,000 IU per pound of body weight per day for several days) will effectively treat not only influenza and the common cold, but help treat a host of other seasonal infections, including meningitis, septicemia, and pneumonia, in both children and adults (emphasis added). source referenced in parent post
Personally, if I have septicemia or bacterial meningitis/pneumonia, I will take whatever the sensitivities say I should. If you choose to treat your N. meningitidis with Vit D, please stay at home so that you don't force everyone else to take prophylaxis.