Types of immunity and vaccination
Types of immunity and vaccination
- Immunity can be active or passive, and natural or artificial.
- A vaccine gives you immunity without the illness.
- Vaccinate enough people and you protect the whole community.
Active vs passive
- Active immunity: your own body meets an antigen and makes its own antibodies and memory cells. Slow to start, but long-lasting.
- Passive immunity: ready-made antibodies are given from outside. Works at once, but does not last (no memory cells).
Practice
Which describes active immunity?
Active immunity = your own response (antibodies + memory cells), so it lasts; passive = ready-made antibodies, short-lived.
Natural vs artificial
| Natural | Artificial | |
|---|---|---|
| active | after an infection | a vaccine |
| passive | antibodies from mother to baby | injection of ready-made antibodies |
Practice
Match each type of immunity to its example.
Active = your own response (infection / vaccine); passive = ready-made antibodies (mother-to-baby / injection).
Vaccination and herd immunity
- A vaccine contains antigens (a dead/weakened pathogen, or part of one).
- They trigger a primary response and make memory cells — long-term immunity without illness.
- If enough people are vaccinated, the pathogen cannot spread easily — protecting even the unvaccinated. This is herd immunity.
Practice
A vaccine gives immunity without illness because it:
The antigens in a vaccine cause a primary response and memory cells — immunity, but without the disease.
Practice
Herd immunity protects unvaccinated people because:
With enough of the population immune, the pathogen has too few hosts to spread, protecting everyone.
You've got it
Key idea
- active = your own antibodies + memory cells (slow, lasting); passive = ready-made antibodies (fast, short)
- natural (infection / mother-to-baby) vs artificial (vaccine / injection)
- a vaccine = antigens → memory cells → immunity without illness
- herd immunity: enough vaccinated → pathogen can't spread → protects everyone