This product as a prophalactic has been more effective than any other previously tried. Took the recommendeded dosage and frequency. Although I've been close to many others - including snotty nosed, spluttering children and grandchildren - since September, other than short lived sore throats, I've avoided all longer term colds and troublesome lung infections. I haven't made any other changes or taken any other products for managing my health so can only assume that it's this product which has been the prime agent for my good fortune.