This is a great product. I am a pre-med student with a focus on nutrition and have studied many health care supplements, and tried a great many too. Out of everything out there, most products are marginally effective, with no real scientific. This product is different because it takes refined immunolin into a powdered form, which is a building block for your body's immune system. What this means is that when your immune system is down, like when you catch cold, this product can help quickly build it back up. More or less, you can take Vitamin C, Echinecea, Zinc, or other things, and they might help, but if I'd still highly recommend you give this product a try.
My understanding is that a large buyer of this product are HIV patients. Not because it cures AIDS, but because HIV and AIDS patients are most damaged - potentially killed, by infection and illness. While most healthy people don't have that situation, most healthy people still can greatly benefit from this product because we don't want to get sick either. And that's just what this product does, prevents sickness, and helps rapidly fight it when you are ill.
There are similar products on Amazon, such as pills that attempt to do the same thing. But buy the powder in this product. The reason why is because of the harsh conditions of the stomach require more than a small dosage. So the 5g of this powder is much more efficient than 1g in pill form. And despite the higher dosage, because of packaging it's less expensive overall as well.