The main reason people are more likely to become sick in the winter is because of vitamin D3 deficiency. When your body gets vitamin D3 your immune system is boosted 5 times stronger. So if your body is vitamin D3 deficient your 5 times more likely to become sick from other people.
So how or where do you get vitamin D3? In the winter people get less sun exposure due tooth shorter days. The sun shining on your skin creates vitamin D3. So less sun exposure equals less vitamin D3 being created. The other way you can get vitamin D3 is by taking supplements. Recommended amount of vitamin D3 supplement is 1000 IU.
So get outside or take vitamin D3 supplement to boost your immune system and reduce your chances of becoming sick during the cold and flu season.