The human body has numerous mechanisms to fight infection. The immune response is how your body recognizes and defends itself against bacteria, viruses, and substances that appear foreign and harmful. In most cases, the immune response will keep you healthy and will prevent infections. But sometimes problems with the immune system can lead to infections, allergies or diseases such as Lupus.
To help prevent infection scientists have developed many vaccines for specific diseases such as whooping cough, measles and polio. Vaccines work by stimulating our immune system to produce antibodies (substances produced by the body to fight disease) without actually infecting us with the disease. This helps to prevent us from getting the infection in future. Allergy occurs when your body mistaken identifies a substance such as grass pollen, as being harmful when in fact it is not. The body then produces a series of actions such as runny nose, sneezing and wheezing to try to combat the grass pollen particles. This is what we call hayfever. There are lots of different types of allergies some are mild and some are serious.