http://articles.mercola.com/sites/ar...etter-way.aspx
snippet:
One credible hypothesis that explains the seasonal nature of flu is that influenza is a vitamin D deficiency disease.
Vitamin D levels in your blood fall to their lowest point during flu seasons. Unable to be protected by the body’s own antibiotics (antimicrobial peptides) that are released by vitamin D, a person with a low vitamin D blood level is more vulnerable to contracting colds, influenza, and other respiratory infections.
Studies show that children with rickets, a vitamin D-deficient skeletal disorder, suffer from frequent respiratory infections, and children exposed to sunlight are less likely to get a cold. The increased number of deaths that occur in winter, largely from pneumonia and cardiovascular diseases, are most likely due to vitamin D deficiency.
Unfortunately, now, for the first time, flu vaccination is also being pushed for virtually all children -- not just those under 5.
video and article on link above.