Here are some immune boosting foods which can be used as a prevention for cold,flu,fever etc -
1.Carrots
It's full of Vitamin A.
2.Yogurt
It is a surprising source of Zinc. Zinc is a good immune booster.
3.Oat meal
Oats is a super food rich in magnesium. Recommending whole grain(fiber rich) oats.
4.Eggs
Eggs are rich in vitamin D.