Vaccination (Cambridge International IGCSE Biology)

Vaccination: Extended

Spec point — 10.1.5 · Explain that active immunity is gained after an infection by a pathogen or by vaccination Outline the process of vaccination: (a) weakened pathogens or their antigens are put into the body (b) the antigens stimulate an immune response by lymphocytes which produce antibodies (c) memory cells are produced that give long-term immunity

Vaccination: Extended

Extended Tier Only

• Vaccinations give protection against specific diseases and boost the body’s defence against infection from pathogens without the need to be exposed to dangerous diseases that can lead to death
• The level of protection in a population depends on the proportion of people vaccinated
• Vaccines allow a dead or altered form of the disease-causing pathogen, which contains specific antigens, to be introduced into the body
• In this weakened state, the pathogen cannot cause illness but can provoke an immune response
• Lymphocytes produce complementary antibodies for the antigens
• The antibodies target the antigen and attach themselves to it in order to create memory cells
• The memory cells remain in the blood and will quickly respond to the antigen if it is encountered again in an infection by a ‘live’ pathogen
• As memory cells have been produced, this immunity is long-lasting

How vaccination works