Types of immunity and vaccination
Introduced| English | Meaning |
|---|---|
| vaccine/vækˈsiːn/ | A preparation that trains the immune system to recognise an antigen and develop protective immune memory. |
| active immunity/ˈæktɪv ɪˈmjuːnɪti/ | Protection arising when a person's own immune system responds to an antigen and develops immune memory. |
| memory cell/ˈmeməri sel/ | A long-lived immune cell that enables a faster or stronger response when the same antigen is encountered again. |
| passive immunity/ˈpæsɪv ɪˈmjuːnɪti/ | Protection provided by antibodies received from another source, rather than produced by the recipient's own immune response. |
| herd immunity/hɜːd ɪˈmjuːnɪti/ | Protection of a whole population when enough people are immune that the pathogen cannot spread. |
Training the body's defences
- Immunity can be active or passive, and natural or artificial.
- A vaccine 疫苗 gives you immunity without the illness.
- Vaccinate enough people and you protect the whole community.
A vaccine gives a person which kind of immunity?
Difficulty 1/5 · 100 coins + a small bonus on first completion today
A vaccine makes the body respond itself, so it builds active, long-lasting immunity.
Active vs passive
- Active immunity 主动免疫: your own body meets an antigen and makes its own antibodies and memory cells 记忆细胞. Slow to start, but long-lasting.
- Passive immunity 被动免疫: ready-made antibodies are given from outside. Works at once, but does not last (no memory cells).
The four kinds of immunity
Passive immunity lasts for life because memory cells are made.
Difficulty 1/5 · 100 coins + a small bonus on first completion today
False. Passive immunity gives ready-made antibodies that act fast, but no memory cells are made, so it is short-lived.
Natural vs artificial
| Natural | Artificial | |
|---|---|---|
| active | after an infection | a vaccine |
| passive | antibodies from mother to baby | injection of ready-made antibodies |
Match each type of immunity to its example.
Difficulty 2/5 · 140 coins + a small bonus on first completion today
Active = your own response (infection / vaccine); passive = ready-made antibodies (mother-to-baby / injection).
Vaccination and herd immunity 群体免疫
- 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.
When most of a population is vaccinated, the pathogen can't spread, protecting the few who aren't
How a vaccine works
Step through it. A vaccine triggers a primary response and memory cells, so the real pathogen meets a fast, strong defence.
A vaccine gives immunity without illness because it:
Difficulty 1/5 · 100 coins + a small bonus on first completion today
The antigens in a vaccine cause a primary response and memory cells — immunity, but without the disease.
Put how a vaccine protects you in order.
Difficulty 3/5 · 200 coins + a small bonus on first completion today
The vaccine trains the immune system in advance, so the real infection is destroyed quickly.
Herd immunity protects unvaccinated people because:
Difficulty 1/5 · 100 coins + a small bonus on first completion today
With enough of the population immune, the pathogen has too few hosts to spread, protecting everyone.
When enough of a population is vaccinated that the pathogen cannot spread, the unvaccinated are protected by ______ immunity.
Difficulty 1/5 · 100 coins + a small bonus on first completion today
Herd immunity protects those who cannot be vaccinated (e.g. babies, the ill) by stopping the pathogen spreading.
You've got it
- 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
Write from a vaccine as artificial active immunity
- A person is injected with a harmless form of an antigen.
- The person later makes memory cells.
What kind of immunity is this?
The exposure is deliberate, and the immune system does the work.
What kind of immunity is a vaccine?
Difficulty 1/5 · 100 coins + a small bonus on first completion today
The body makes its own memory after a planned exposure.