Biology - Vaccines

• Vaccination


  1. Introducing small quantities of dead or inactive forms of a pathogen into the body

  2. Stimulating the white blood cells to produce antibodies

  3. If the same pathogen re-enters the body, the white blood cells respond quickly to produce the correct antibodies, preventing infection
• Antibiotics


  Medicines that help to cure bacterial disease by killing infective bacteria inside the body
• It is important that specific bacteria should be treated by specific antibiotics
• The use of antibiotics has greatly reduced deaths from infectious bacterial diseases
• The emergence of strains resistant to antibiotics is of great concern
• Antibiotics cannot kill viral pathogens
• Painkillers and other medicines are used to treat the symptoms of disease but do not kill pathogens
• It is difficult to develop drugs that kill viruses without also damaging the body's tissues
• Traditionally drugs

  Were extracted from plants and microorganisms
• Drugs originating from plants

  • The heart drug digitalis originates from foxgloves
  • The painkiller aspirin originates from willow
• Drugs originating from microorganisms

  • Penicillin was discovered by Alexander Fleming from the Penicillium mould
• Most new drugs are synthesised by chemists in the pharmaceutical industry
• The starting point for new drugs may still be a chemical extracted from a plant
• New medical drugs testing

  1. Tested and trialled before being used to check that they are safe and effective

  2. Extensively tested for toxicity, efficiency and dose

  3. Preclinical testing is done in a laboratory using cells, tissues and live animals

  4. Clinical trials use healthy volunteers and patients

  5. Very low doses of the drug are given at the start of the clinical trial

  6. If the drug is found to be safe, further clinical trials are carried out to find the optimum dose for the drug

  7. In double blind trials, some patients are given a placebo