How do vaccinations work? Relating to humoral immunity and the secondary immune response.

The body has both humoral and cell mediated immunity. A vaccination involves injecting a patient with inert (Inactivated) or dead material from a pathogen, be that a bacterium or a virus. Once injected into the body the immune system recognises this pathogen as a foreign body. B-cells are a type of white blood cell found in our body that have antibody receptors on their surface. These antibody receptors recognise antigens presented on the surface of the foreign pathogen. The antibody receptor fits like a glove to only one type of antigen and hence allows for identification of a specific pathogen. The antibody-antigen complex then leads to ‘activation’ of these B-cells and causes them to proliferate and divide by mitosis to produce many clones of the same B-cell. Many of the clones are active effector B-cells that go on to help remove the pathogen, while another type of B-cell is produced, the memory cells. This initial immune response is known as the primary immune response. These memory cells ‘remember’ the antigen they recognised and reside in the body. They are then ready to instantly recognise the antigen if it was to come into the body again, aka when a person is infected with the pathogen, not through vaccination. These memory cells quickly recognise the pathogen and rapidly divide and produce plasma cells to tag and destroy the pathogen. Therefore the vaccination allows the immune system to be primed and produce memory cells that are able to recognise and ‘remember’ a pathogen. This means that if the individual is infected with the same pathogen they are able to produce a much larger and quicker response to clear the infection, this response is known as the secondary immune response.