Vitamin D and H1N1

There was an H1N1 outbreak at Central Wisconsin Center (CWC) a long-term care facility for people with developmental disabilities. This centre has 275 residents and approximately 800 staff. Serum 25-OHD has been monitored in virtually all residents for several years and all patients were supplemented with vitamin D. In June, 2009, at the time of a spike of H1N1 in Wisconsin, two residents had positive tests for H1N1, on the other hand, 60 staff members were tested and found to have H1N1, and another 43 called in sick with H1N1 type symptoms. So, it is remarkable that only two residents of 275 developed H1N1, while 103 of 800 staff members had contracted it. It appeared that the staff were much more susceptible to the H1N1 virus due to their lack of Vitamin D supplementation. Even if the 43 staff members who called in sick with symptoms were excluded, 0.73% of residents were affected, as compared to 7.5% of staff. This 10-fold difference was statistically significant (P<0.001). That is, the chance that this was a chance occurrence is one less than one in a thousand.

Vitamin D acts as an immune modulator and stimulates immune fighting cells such as neutrophils, monocytes and natural killer cells in the epithelial cells which line the respiratory tract.
A good study on vitamin D and the flu: