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
