Vaccination

• provides immunity to specific diseases

  • created by deliberate exposure of antigenic material that has been rendered harmless → usually infected, some cases orally
  • the antigenic material is treated as a real disease by immune system → as a result, the immune system is activated + manufactures antibodies
  • memory cells (memory cells provide long-term immunity)
• antigenic material used in vaccines can to variety of forms:

  • whole live microorganisms - usually ones that are not as harmful as those that cause the real disease (but they must have very similar antigens, so antibodies produced will be effective against real pathogen)

  • harmless er attenuated (weakened) version of pathogenic organism (e.g. measles + TB vaccines)
  • a preparation of antigens from a pathogen (e.g hepatitis B)
  • a toxoid, harmless version of toxin (e.g. tetanus vaccine)
• Application of vaccines

  • Herd Vaccination
  • Ring vaccination
• Herd Vaccination

  using vaccine to provide immunity to all or almost all of population at risk

  • once enough people are immune, the disease con no longer the spread through the population + achieve "herd immunity' → in order to be effective, it is essential to vaccinate almost all population
  • to eradicate smallpox, it was necessary to vaccinate 80-85% of population

  →estimated at least 95% would need to be immunised

  In the UK, there’s a vaccination programme to immunise young children against some diseases
• Ring Vaccination

  used when a new case of a disease is reported

  • involves vaccinating all the people in the immediate vicinity of the new case(s)

  →this may mean vaccinating the people in the surrounding houses, or even whole village/town

  • used in many parts of the work to control spread of livestock disease
• Control of epidemics

  once a disease has been eradicated, or reduced to such allow incidence that is unlikely to spread, routine vaccination is relaxed

  • occurred with smallpox; TB vaccinations have also stopped for most children in UK

  → however some pathogens can undergo genetic mutations which change their antigen + memory cells produced by vaccination may not be recognised by the new antigens. When this occurs the pathogen may be transmitted + incidence of disease increases
• Control of epidemics 2

  • Certain pathogens such as influenza virus, are relatively unstable + regularly undergo changes in their antigens

  → when this occurs; an epidemic may arise

  threats from epidemics must be monitored so that new strains of pathogens can be identified

  → this enables health authorities to prepare for an impending epidemic by stockpiling suitable vaccines + vaccinating people who are at particular risk from disease
• Influenza

  ‘flu’ is a killer disease caused by a virus

  • people over 65 + those with respiratory tract conditions are particularly at risk

  Occasionally, a new strain of flu virus arises that is particularly virulent, cause an epidemic.

  In attempts to avoid another worldwide pandemic, people at risk are immunised. In UK, there’s a vaccination programme to immunise all over 65 were vaccinated, and those who are at risk.
• Influenza 2

  • new versions of the influenza vaccination have been developed which can be administered via a nasal spray

  →proposed that these will be offered to all children in the coming years

  →the strains of flu used in this immunisation programme change each year

  →worldwide research is undertaken to determine which of the strains of flu are most likely to spread in any given year
• Different types of immunity

  Immunity can be achieved naturally or artificially. Natural immunity is achieved through normal life processes. Artificial immunity is achieved through medical abbreviation.

  Immunity can be achieved actively or passively.

  • Active immunity is achieved when the immune system is activated + manufactures its own antibodies
  • Passive immunity is achieved when the antibodies are supplied from another source

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