Explain how vaccines work.

Vaccinations are an injection of small amount of a dead or weakened form of a pathogen that provoke a primary immune response. This causes the body to produce the correct antibodies to remove the pathogen. The production of these antibodies leads the production of memory cells that exist in the body for a long time. If the same pathogen enters the body again, these memory cells produce the correct antibody in what is known as the secondary immune response, which is much faster than the primary response and the patient shows no symptoms.