Vaccinations (Edexcel IGCSE Biology)

Revision Note

Lára Marie McIvor

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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 Marie McIvor

Author: Lára Marie McIvor

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.