You can support immunity by correcting deficiencies, sleeping and being active. No product meaningfully 'boosts' a healthy immune system — and an overactive one causes allergies and autoimmunity.
Evidence & sources
Correcting a nutrient deficiency supports immune function, but there is little evidence that extra supplements improve immunity in well-nourished people. Evidence: moderate. Known: Review of clinical studies. Unknown: Some specific uses (e.g., zinc for cold duration) have mixed evidence. Source: NIH Office of Dietary Supplements, Dietary Supplements for Immune Function and Infectious Diseases (Current revision).