How do vaccines work? – Molecules Zone

Question: How do vaccines work?
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- Royal Society of Chemistry: Find out more about:
  
  vaccine
Asked by Fiona Mansell to Alex, Anaïs, Peter, Shreesha on 18 Mar 2015.
- Peter Maskell answered on 18 Mar 2015:
  
  They are basically dead viruses (or bits of viruses) that activate the immune system and allow it to recognise the live virus.
- Shreesha Bhat answered on 18 Mar 2015:
  
  vaccines contain an agent that resembles a disease-causing microorganism and is often made from weakened or killed forms of the microbe. When you inject a vaccine, the body’s immune system (which has memory cells) memorises the microbe, and if that virus/bacteria does really enter the body, the immune system launches a full scathing attack on the bacteria/virus.
- Anaïs Pujol answered on 19 Mar 2015:
  
  Vaccine is here to help your immune system to fight against a pathogen host. Imagine that your body had a self-defence class to be prepared and not surprised by an attack. Everyday your organism is exposed to pathogens, but we are basically protest by our immune system, however when you are tired or when you got an injury this is an opportunity for any pathogen to get inside your body.
  You can have vaccine for virus but also for bacteria. In the first case against virus it will be an inactive virus (alive virus but weaker) which will be used, for bacteria, we will use inactive toxin.

Question: How do vaccines work?