Antigens, antibodies and active immunitySpec B10.1.7, B10.1.8
In short
Antibodies have a shape complementary to one specific antigen; active immunity is defence by antibody production, gained by infection or vaccination.
Active immunity is defence against a pathogen by antibody production in the body. It is gained in two ways:
- after an infection by a pathogen (the body makes antibodies and recovers)
- by vaccination
Quick check
Supplement What is active immunity?
Show answer
Defence against a pathogen by antibody production in the body.
Supplement State two ways in which active immunity is gained.
Show answer
After an infection by a pathogen, and by vaccination.
Written and checked against the Cambridge IGCSE Combined Science (0653) specification · Updated October 2026