Lesson 4 ·Class 9 · Aids to Health · Flow Lab
Vaccination and Immunisation
How a vaccine trains the body in advance.
A vaccine gives the body a rehearsal, so the real infection is not the first meeting.
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💉 Step 1 of 6 · The vaccine is given
A weakened, killed or partial germ is introduced. It carries antigens but cannot cause the disease.
Free play — step through the process at your own pace, and move the slider to see what changes. Switch to when you're ready to test yourself.
A vaccine gives ACTIVE immunity — your own body makes the antibodies, so the protection lasts. Ready-made antibodies in an antiserum give passive immunity, which is fast but short-lived.
What this lesson covers
Challenges to clear
- Advance to what makes the protection last.
- Step through the whole response.
The task
A vaccine gives the body a rehearsal, so the real infection is not the first meeting.
What this lesson covers
- The vaccine is given — A weakened, killed or partial germ is introduced. It carries antigens but cannot cause the disease.
- Antigens recognised — Lymphocytes recognise the antigens as foreign.
- Antibodies made — B-lymphocytes multiply and produce antibodies specific to that antigen — each antibody fits only one.
- Memory cells remain — After the antigens are cleared, memory cells stay behind for years. This is active acquired immunity.
- The real germ arrives — Memory cells recognise it at once and flood the blood with antibodies far faster and in far greater numbers.
- Illness prevented — The germ is destroyed before it can multiply enough to make you ill.
Hint
A vaccine gives ACTIVE immunity — your own body makes the antibodies, so the protection lasts. Ready-made antibodies in an antiserum give passive immunity, which is fast but short-lived.