Types of Immunity and Vaccinations (A-level Biology)

Types of Immunity

• Natural Immunity: occurs naturally when the body is exposed to a pathogen
• Artificial Immunity: acquired through vaccination or injection of antibodies from another animal

Active and Passive Immunity

Active Immunity

• Develops when the body makes its own antibodies in response to pathogen exposure
• Results in long-term immunity

Passive Immunity

• Develops due to antibodies from another animal
• Provides short-term immunity
• Can be acquired through vaccination or injection of antibodies from another animal

Importance of Vaccination

• Leads to Herd Immunity: when a sufficient percentage of the population is immunized, the spread of disease is prevented

Ethics of Vaccination

• Raises ethical concerns about the importance of individual freedom versus the greater good of public health

Risks of Vaccines

• May have side effects or allergic reactions
• Can lead to antigenic variability

Antigenic Variability

• The ability of pathogens to change their antigens to evade the host's immune mechanisms
• Examples include:
  • Influenza Virus
  • Tuberculosis
  • HIV
• An example of the evolutionary race between pathogens and hosts

Evolutionary Race between Pathogens and Host

• Pathogens evolve to evade host immune mechanisms
• Hosts adapt to combat pathogens
• Antigenic variability is a key strategy used by pathogens in this evolutionary race