Vaccination (AQA GCSE Biology): Revision Note

Why vaccinate?

• Vaccination can prevent illness in individuals, as well as preventing the spread of pathogens within a population

• If a large number of the population are vaccinated, it is unlikely that an unvaccinated individual will become infected with the pathogen

  • This is the principle of herd immunity

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Evaluating vaccination

Advantages:

• Smallpox has been eradicated in the global population due to a successful vaccination programme

• Diseases that were once common are now relatively rare due to widespread vaccinations, e.g.:

  • polio

  • measles

• Epidemics can be prevented if a large number of the population are vaccinated

Disadvantages:

• The vaccine may not be 100 % effective

• Vaccines may result in side-effects, such as:

  • pain at the injection site

  • flu-like symptoms

• Vaccines are only effective if enough of the population is vaccinated

  • People choosing not to be vaccinated can therefore cause resurgence of a disease

How do vaccines work?

• Vaccination involves:

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

  2. the stimulation of white blood cells to produce specific antibodies

     • this is the primary response

  3. the immune system responding quickly to produce the correct antibodies if the same pathogen enters the body again

     • this is the secondary response

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Measuring antibody production

• We would expect to see:

  • An initial peak of antibody production immediately after vaccination; this is the primary response

  • A second, larger, steeper peak of antibody production after coming into contact with the same pathogen again; this is the secondary response

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