I am a big fan of this stuff. My sister who travels extensively in the third world turned me onto it. I haven't' had more than a twinge of the flu or a cold in years. it is an immunity builder, you start taking it at the first sign of illness, or you can take it for maintenance. I do the maintenance dose when everyone one around me is coming home with the crud. Works for me.

http://www.sourcenaturals.com/products/GP1345.html