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Immunity
Active vs passive immunity
Do you make the antibodies yourself, or borrow ready-made ones? That single question splits active from passive.
Active immunity
Your own system meets an antigen — a microbe or a vaccine — and makes its own antibodies and memory cells. Slow to build, but long-lasting.
Passive immunity
Ready-made antibodies are handed to you — across the placenta, in mother's milk, or as an injected antiserum. Instant protection, but short-lived and with no memory.
The trap
Speed vs durability gives it away. Active = you make it, slow but lasting (with memory). Passive = borrowed, instant but temporary (no memory). A tetanus antitoxin is passive; the tetanus vaccine is active.
Quick check
Antibodies passed to a baby through mother's milk give the baby:
- AActive immunity
- BPassive immunity
- CInnate immunity
- DNo immunity