Vaccines

• What is passive immunity?

  • Antibodies introduced into body.
  • Plasma cells and memory cells are not made.
  • No long term immunity.
  • This is FASTER than active immunity.
  • e.g. from a mother to child through breast milk.
• What is active immunity?

  • Created by immune system after exposure to a pathogen or its antigen.
  • Natural: following infection, the body creates antibodies and memory cells.
  • Artificial: following introduction of a weakened version of the pathogen/antigens through a vaccine.
• What do vaccines contain?

  Small amounts of a weakened or dead pathogen.
• Exposure to the antigens in a vaccine cause B cells to...

  Be activated and undergo clonal selection.
• How to vaccines lead to immunity?

  1. Vaccine is injected
  2. B cells are activated and divide, creating plasma cells and memory cells.
  3. The memory cells divide rapidly if re-infection occurs and the antibodies destroy the pathogen before symptoms occur.
• What is the concept of herd immunity?

  If enough of the population is vaccinated, the pathogen cannot easily spread through the population. This provides protection for those who are not vaccinated.