Vaccination

• Vaccination is the main technique for helping the immune system recognise and destroy pathogens. Immunising (making immune) a large proportion of the population will make it very hard for a pathogen to be spread.
• Immune system recognition

  • White blood cells recognise that the antigens are foreign and produce antibodies against them.
• Memory cells

  • Some of these white blood cells remain in the blood as memory cells. If the same pathogen invades the body again, the memory cells are able to:
  • Produce antibodies faster.
  • Produce more antibodies, meaning that the antibody concentration remains in the blood for longer.
• Immunity

  • Next time the same pathogen infects the vaccinated person, it will be destroyed by the immune system before it can cause illness.
  • Vaccinating a large proportion of the community to protect everyone in the community is known as herd immunity.
  • Vaccinating the majority of people makes it hard for the pathogen to spread.
• Inject a dead pathogen

  • A vaccination injects a dead or inactive form of a pathogen into the blood.
• Herd Immunity

  If we immunise a large proportion (or percentage) of the population, this makes it very hard for a pathogen to be spread. This is called herd immunity.