Types of Immunity

Definition

The body's defence against disease-causing organisms, classified by whether it is present from birth or developed later, and by how it is acquired.

Key points

• Innate (non-specific) immunity is present from birth and acts the same against all pathogens; it includes skin, mucus, stomach acid, and white blood cells that engulf microbes.
• Acquired (adaptive, specific) immunity develops after exposure to a particular pathogen and produces antibodies and memory cells targeted at that pathogen.
• Active immunity is produced by the body's own response, either naturally (after an infection) or artificially (after a vaccine); it is slow to develop but long-lasting.
• Passive immunity is borrowed from outside, either naturally (antibodies passed from mother to baby through placenta and breast milk) or artificially (injection of ready-made antibodies or antiserum, as in anti-rabies or anti-snake-venom treatment); it acts at once but is short-lived.
• Vaccines work by stimulating active immunity without causing the full disease.

Why it matters for CAPF

The innate versus acquired distinction and the active versus passive distinction, with their natural and artificial examples, are repeatedly tested biology facts, and immunity underpins vaccination policy.

Common confusion

Active immunity is slow but long-lasting, while passive immunity is immediate but short-lived; do not swap their speed and duration. Vaccines give active immunity (the body makes its own antibodies), whereas an antiserum injection gives passive immunity (ready-made antibodies).

Related concepts

concept vaccines and immunity, concept types of vaccines, concept monoclonal antibodies

Parent note

diseases and public health