Vaccines

• Vaccination


  Developed throughout history to protect both humans and animals from a wide range of preventable and potentially serious illnesses
• Immunological memory


  The ability of the immune system to develop resistance to infection with the same pathogen in the future after initial exposure
• Adaptive immune system


  • Contains white blood cells known as T and B lymphocytes
  • These become activated during the first time or primary exposure to a pathogen
  • Population of these T and B lymphocytes known as memory cells remain in the individual
  • These memory cells remain on standby ready to react quickly when the individual is reexposed to that particular pathogen
• Secondary exposure


  When an individual is reexposed to a particular pathogen
• Immunological memory


  Helps the immune system respond much more rapidly and effectively than during the primary exposure, protecting the individual from the development of disease symptoms
• Vaccines


  Generate the memory effect artificially and at an early stage to prevent future disease
• Vaccine administration


  1. Inject a weakened version of pathogens, inactive pathogens, or just particular parts of pathogens into the individual

  2. In healthy individuals, these vaccine components activate a specific immune response mimicking primary infection but weak enough not to cause the development of disease symptoms
• Vaccine example


  • Varicella (Chickenpox) vaccine involves injection of a weakened version of the varicella zoster virus
• Vaccination prevents and controls the spread of a wide range of illnesses including polio, smallpox, whooping cough, measles, and the seasonal influenza virus
• All credible scientific evidence strongly supports the importance of vaccination in avoiding preventable illness in individuals and populations