vaccines

• Insertion of antigens

  • Vaccines insert the antigens for a specific disease into the individual.
  • The antigens can be inserted by:
  • Injection.
  • Oral insertion (oral vaccinations may be broken down in the stomach).
• Primary immune response

  • The presence of antigens in the body induces the primary immune response.
  • The antigens are inserted as a dead or weakened pathogen so the vaccine does not give rise to a full-scale infection with symptoms.
• memory cells

  • The primary immune response leads to the production of memory cells.
• Immunity

  • Memory cells provide immunity.
  • If the individual is infected by a living pathogen, the memory cells will be ready to induce a fast, strong secondary response.
• Booster vaccinations

  • Booster vaccinations can be given over time to make sure the memory cells are still in the body.
• Continuous trial

  • Some vaccinations are continuously being changed because the antigens are evolving at a very rapid rate.
  • Pathogens evolve to avoid detection by the immune system. This causes a problem because it makes the vaccines useless.
  • Pathogens with a high mutation rate (e.g. influenza and HIV) are the most difficult to vaccinate against.
• herd immunity:

  Spread of a pathogen

  • Herd immunity works if a large proportion of the population is vaccinated against a disease.
  • If most of the population are immune, the chance of someone without immunity coming into contact with the disease is reduced.
• herd immunity:

  Population requirements

  • Herd immunity is the basis of widescale vaccination programs.
  • If the disease is highly contagious (e.g. measles), over 90% of the population must be vaccinated.
  • If the disease is less contagious (e.g. polio), over 80% of the population must be vaccinated.
• herd immunity:

  Benefit

  • Herd immunity offers protection for the most vulnerable people in a population (e.g. new born babies and the elderly).
• herd immunity:

  Herd immunity is the concept that if enough people in a population have immunity against a disease, the entire population are less likely to be infected.
• Passive immunity

  • Passive immunity is where an individual receives antibodies from an external source. The antibodies are not made by the individual.
  • Passive immunity can be:
  • Natural (antibodies are transferred to a baby from its mother in breast milk).
  • Artificial (antibodies are transferred to an individual by injection).
• Active immunity

  • Active immunity is where the immune system has created its own antibodies.
  • Active immunity can be:
  • Natural (antibodies have been created in response to catching a disease).
  • Artificial (antibodies have been created in response to vaccination of antigens).
• Immunity can be provided in an active or a passive way. Active and passive immunity can also be artificial or natural.