vaccination

• Passive immunity


  • Antibodies not created naturally by body (e.g. Injected)
  • No exposure to pathogen, so plasma & memory cells not made
  • Fast acting but no long-term immunity
  • Antibodies can be passed to fetus through placenta or baby through breast milk
• Active immunity


  Created by own immune system after exposure to pathogen/its antigen
• Types of active immunity


  • Natural active immunity (following infection & creation of own antibodies & memory cells)
  • Artificial active immunity (following introduction of weakened version of pathogen/antigen via vaccine)
• Antigen variability


  • Pathogens' DNA can mutate
  • If mutation occurs in gene which codes for antigen, antigen shape changes
  • Immunity/memory B cells (with old shape) no longer effective
  • New flu vaccine creation every year as the virus mutates and changes antigen very quickly
• Vaccines


  Small amount of weakened/inactive pathogen or antigens introduced in mouth or by injection
• Herd immunity


  Large population vaccinated so pathogen cannot spread easily among that population, protecting unvaccinated (due to medical reasons)