AQA GCSE Biology

Revision Notes

3.1.7 Vaccination

Why Vaccinate?

  • Vaccination will prevent illness in an individual by providing artificial immunity
  • Vaccination involves exposing an individual to the antigens of a pathogen in some form, triggering an immune response which results in the formation of memory cells which can make antibodies against it
  • If a vaccinated individual is infected with the pathogen, they can destroy it before they become infectious
  • Consequently, vaccines reduce the likelihood that an infected individual will spread the pathogen they have been vaccinated against to others
  • 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 behind the idea of herd immunity
  • There are three main scenarios with vaccination:
    • There are no vaccinations and the disease spreads quickly
    • Some of the population are vaccinated and the disease spreads to less people
    • Most of the population are vaccinated and this prevents the spread

Herd_immunity, IGCSE & GCSE Biology revision notes

Herd immunity protects the vulnerable that may not be able to have the vaccine

Worldwide vaccination

  • The role of the WHO is to monitor global diseases, they will track if a disease is endemic, epidemic or pandemic
  • The importance of vaccines cannot be underestimated:
    • The number of people with measles worldwide is increasing even though there is a vaccine
    • The increase is due to a drop in the vaccination rate globally – there was some controversy over the MMR vaccine in 1998 and the number of vaccinations dropped significantly after this
  • Vaccines have reduced drastically the cases of diseases worldwide

Vaccination statistics table

Vaccination statistics table, downloadable IGCSE & GCSE Biology revision notes

Data source: ourworldindata.org/vaccination

Advantages & disadvantages of vaccination table

Advantages and disadvantages of vaccination table, downloadable IGCSE & GCSE Biology revision notes

How do Vaccines Work?

  • Vaccination involves introducing small quantities of dead or inactive forms of a pathogen into the body to stimulate the white blood cells to produce antibodies
  • If the same pathogen re-enters the body the white blood cells respond quickly to produce the correct antibodies, preventing infection

 

Vaccination, IGCSE & GCSE Biology revision notes

The process of long-term immunity by vaccination

  • There are two types of immunity:
    • Active immunity that comes from the body creating antibodies to a disease either by exposure to the disease (natural) or by vaccination (artificial)
    • Passive immunity that comes from antibodies given to you from another organism, for example in breast milk
  • With the measles vaccine, for example, vaccination with a weakened form of the measles virus results in the production of antibodies and memory cells
  • When exposed to the virus naturally and infected, an individual can produce a higher concentration of antibodies much more quickly to destroy it

 

Vaccination graph, downloadable IGCSE & GCSE Biology revision notes

Graph showing the number of measles antibodies in the blood following vaccination and infection

Author: Jenna

Jenna studied at Cardiff University before training to become a science teacher at the University of Bath specialising in Biology (although she loves teaching all three sciences at GCSE level!). Teaching is her passion, and with 10 years experience teaching across a wide range of specifications – from GCSE and A Level Biology in the UK to IGCSE and IB Biology internationally – she knows what is required to pass those Biology exams.
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