(6) Vaccination

• immunity is the ability of an organism to resist infection
• there are two forms of immunity :

  • Passive Immunity
  • Active Immunity
• Passive immunity :

  • produced by the introduction into individuals from an outside source
  • no direct contact with the pathogen or its antigen is necessary to induce immunity
  • immunity is acquired immediately
  • antibodies not produced by individuals themselves
  • Antibodies not replaced when they are broken down
  • no memory cells formed - no lasting immunity
• passive immunity does not require direct contact with the pathogen or its anitgen to induce immunity
• in passive immunity, immunity is required immediately
• in passive immunity, antibodies are not replaced when they are broken down + non memory cells are formed so no lasting immunity
• anti-venom is an example of passive immunity
• since the antibodies die after a short time, passive immunity is not long lasting as the body did not produce the antibodies themselves so no memory cells were produced
• Active Immunity :

  • produced by stimulating the production of antibodies by the individuals own own immune system
  • direct contact with the pathogen or its antigen is necessary
  • immunity takes time to develop
  • generally long lasting
• active immunity is long lasting
• passive immunity is short lasting
• active immunity involves antibodies being produced by the individuals own immune system
• active immunity requires direct contact with the pathogen or its antigen
• immunity takes time to develop
• passive immunity involves antibodies being introduced to the individual from an outside source
• There are two types of Active Immunity :

  • Natural Active Immunity
  • Artificial Active Immunity
• Natural Active Immunity :

  • results from an individual becoming infected with a disease under normal circumstances
  • body produces its own antibodies
  • body may produce antibodies for many years
• Artificial Active Immunity :

  • forms the basis of vaccination
  • involves inducing an immune response in an individual
  • individual does not suffer symptoms of the disease
• Example of Artificial Active Immunity :

  • vaccination
• Example of Natural Active Immunity :

  • exposure to pathogen (air, water, mixture of bodily fluids-needles, sneezing, coughing)
  • infection with pathogen
• Example of Natural Passive Immunity :

  • antibodies passing across the placenta from the mother
  • breastmilk
• Examples of Artificial Passive Immunity :

  • anti-venom
• Active :

  • contact with pathogen
  • memory cells
  • longer lasting
• Passive Immunity :

  • transfer of antibodies
  • not long lasting
• Exposure to Pathogen :

  • air
  • water
  • mixture of bodily fluids (needles)
  • sneezing (droplets in air)
  • coughing (droplets in air)
• vaccination is the introduction of the appropriate disease antigens into the body, either by injection or by mouth
• vaccinations are meant to stimulate an immune response against a particular disease
• vaccinations include a dead or inactive form of the pathogen
• the inactive/ dead pathogen in the vaccination stimulates the immune response
• after vaccination, the response is only slight because only a small amount of antigen is injected/ introduced
• vaccinations rely on memory cells being produced
• memory cells remain in the body and allow a greater and more immediate response to a future infection with the pathogen
• vaccinations allow for a rapid production of antibodies and the new infection is rapidly overcome before it can cause any harm
• vaccination is the introduction of antigens to stimulate an immune response
• Vaccinations :

  • dead or inactive form of pathogen injected
  • antigens trigger an immune response.
  • B lymphocytes are activated
  • plasma and memory cells produced
  • antibodies produced
  • memory cells remain
  • if pathogen is encountered, they'll divide and produce plasma cells rapidly
  • long term immunity
• when carried out on a large scale, vaccinations provide protection against disease not only for individuals but also for the whole population
• vaccines prevent a disease not cure it
• successful vaccination programmes :

  • vaccine must be economically available - in sufficient quantities to immunise most of the vulnerable population
  • need few side effects - otherwise may discourage people from receiving vaccine
  • need means of producing, storing and transporting vaccine - involves technologically advanced equipment, hygienic conditions, refrigerated transport
  • need means of administering the vaccine - trained staff
  • need to vaccinate most of the vulnerable population to produce herd immunity
  • public belief
• herd immunity = when a sufficiently large population of the population has been vaccinated to make it difficult for a pathogen to spread within that population
• herd immunity relies on the idea that pathogens are passed from individual to individual when in close contact