It could benefit from an edge, a nudge, some extra resources to keep you healthy. Supplements, surprising treatments, immunity-boosting vaccines and even exercises can help the immune system do its job. The big question is, Which ones work best? Tons of supplements and vitamins that promise to aid immunity line drugstore and supermarket aisles, and friends and family all have their favorite teas and creams they swear will help. Choices can be bewildering.