How do Vaccines Work? (WJEC GCSE Biology)

How Vaccines Protect Against Infection

Higher Tier Only

• Vaccines can be given to protect people from the harmful symptoms of some bacterial or viral infections

• Vaccines use bacterial or viral particles that are grown in a lab before being rendered harmless

• They generally contain either:

  • Specific antigens derived from a pathogen

  • Parts of antigens

  • Non-active microorganisms, such as dead or weakened virus particles

• These antigens or dead microorganisms are introduced into the body, usually in the form of an injection

• Antigens and microorganisms in this form 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 which will then 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 vaccinations cause immunity

Vaccination