How does a vaccine work?
A vaccine works by introducing a small amount of a dead or inactive pathogen, so the immune system makes antibodies and memory cells without you getting ill.
GCSE Biology
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
In more detail
A vaccine contains a dead or weakened form of a pathogen (or its antigens). When injected, the antigens are recognised by white blood cells (lymphocytes), which produce specific antibodies and, importantly, memory cells. If the real pathogen infects you later, the memory cells recognise it and produce the correct antibodies quickly and in large amounts, destroying the pathogen before you become ill — this is immunity.
Key points for the exam
- Contains dead/inactive pathogen or antigens.
- Lymphocytes make antibodies and memory cells.
- On re-infection, memory cells respond faster and stronger → immunity.
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