It is winter in New England and the temperatures are in the single digits and many of my coworkers are sick. I'll just strengthen my immune system by eating more organic fruits and veggies, and getting plenty of sleep and exercise. This has worked for me for the past 48 years.
Time for the disclaimer: I am not a doctor. I do not play one on TV. I did not stay in a Holiday Inn Express last night. The great thing about living in this country is the freedom and ability to do our own research and make our own choices regarding health and nutrition.