Vaccination (Cambridge O Level Biology)

• Vaccinations give protection against specific diseases and boost the host’s defence against infection from pathogens without the need to be exposed to dangerous diseases that can lead to death
• The level of protection in a population depends on the proportion of people vaccinated
• Vaccines allow a weakened form of the disease-causing pathogen, which contains specific antigens, to be introduced into the body
• In this weakened state, the pathogen is harmless and cannot cause illness
  • But it can provoke an immune response
  • There are sometimes mild symptoms of the disease after vaccination, but not the full-scale disease
• Lymphocytes produce complementary antibodies for the antigens
• The antibodies target the antigen and attach themselves to it in order to create memory cells
• The memory cells remain in the blood and will quickly respond to the antigen if it is encountered again in an infection by a ‘live’ pathogen
• As memory cells have been produced, this immunity is long-lasting

Vaccination Process Diagram

Vaccination