Vaccinations (Edexcel IGCSE Biology)

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Vaccinations

  • Vaccines are used to induce immunity to infectious diseases
    • They have reduced the cases of certain diseases drastically or even eradicated many diseases worldwide
      • This includes smallpox, measles, mumps and tetanus amongst many others
  • A vaccine contains harmless versions of a pathogen
  • There are several different methods by which scientists ensure that vaccines contain harmless pathogens such as:
    • Killing the pathogen
    • Making the pathogen unable to grow or divide (attenuated vaccine)
    • Using fragments of pathogens, rather than whole cells
  • A vaccine may be administered orally, nasally or via an injection

How vaccines work

  • Once in the bloodstream, the antigens contained within the vaccine can trigger an immune response in the following way:
    • Lymphocytes recognise the antigens in the bloodstream
    • The activated lymphocytes produce antibodies specific to the antigen encountered
    • Memory cells are produced from the lymphocytes
    • Memory cells and antibodies subsequently remain circulating in the blood stream

Vaccination, IGCSE & GCSE Biology revision notes

The process of long-term immunity by vaccination

  • Future infection by the same pathogen will trigger a response that is much faster and much larger compared to the initial response
  • Due to the rapid nature of the response, the pathogen is unable to cause disease and the individual is said to be immune

Vaccination graph, downloadable IGCSE & GCSE Biology revision notes

Graph showing the number of measles antibodies in the blood following vaccination. The secondary response is much faster and a greater number of antibodies are produced.

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Lára

Author: Lára

Expertise: Biology Lead

Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.