Explain how the process of vaccination actively prevents severe illness in an individual by safely stimulating the immune system.
Describe the biological mechanism of vaccination, which involves introducing small quantities of dead or inactive forms of a pathogen into the body to deliberately trigger white blood cells to produce specific antibodies.
Understand that upon subsequent natural re-infection by the same active pathogen, the immune system's prepared white blood cells rapidly produce the correct antibodies, effectively preventing a full infection.
Explain the sociological concept of herd immunity, understanding how immunising a large proportion of a population significantly reduces the overall spread of pathogens.
