# Types of immunity

Source: https://projectalevel.co.uk/biology/immunity/types_of_immunity

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- Natural active: Occurs during infection. It is active because lymphocytes are activated by antigens on pathogen's surface.
- Artificial active: Injecting or taking antigens by mouth. Takes time for T and B cells to be activated but gives long lasting immunity.
- Natural passive: Mother to child through placenta or milk.
- Artificial passive: Used during potentially fatal diseases. Provides an instant response but only temporary as antibodies are not the body's own so memory cells are not created. E.g. tetanus - injection of antitoxins given.
- Memory cells are only produced in active immunity.
- Protection for active immunity is permanent whereas in passive immunity it is only temporary.
- Antigens are only encountered in active immunity.
- Active immunity takes several weeks to become active but passive is immediate.