Why do flu epidemics in Europe only occur in winter?

Researchers in New York believe they have solved one of the great mysteries of the flu: Why does the infection spread primarily in the winter months? ... read more

Not only in winter, mostly it happends on the end of autumn /beginning of winter. Weather can change very suddenly, also happends there is rain/wind. Cold makes your immune system weaker, so easily can get flu. read more

That is, something may be regularly reducing our immunity every fall and winter. J Hyg (Lond). 1981 Feb;86(1): 35-47. In 2003, researchers confirmed that influenza epidemics in the tropics occur, with few exceptions, during the rainy season - when vitamin D levels should be falling. Paediatr Respir Rev. 2003 Jun;4(2): 105-11. read more