Practice for the immune system
A vaccine trains the body before the real germ arrives.
Drops and injections
When you were small, you may have taken drops or injections for polio, measles, tetanus or hepatitis. You were not ill at the time.
Why take a vaccine when you are not ill?
What this lesson covers
The idea
A vaccine trains the immune system to recognise and attack harmful germs, giving acquired immunity — protection developed after exposure to a pathogen or a vaccine.
Drops and injections
When you were small, you may have taken drops or injections for polio, measles, tetanus or hepatitis. You were not ill at the time.
Why take a vaccine when you are not ill?
- To train the body before the real germ comes
- To cure a disease you already have
- To make all germs disappear
Train the immune system
Give the vaccine to the child on the right. Then let the real germ arrive.
Acquired immunity
A vaccine trains the immune system to recognise and attack harmful germs. It gives acquired immunity: protection developed after exposure to a pathogen or a vaccine.
- Step | What happens
- Vaccine is given | The immune system is trained to recognise and attack the germ
- The real germ arrives | The trained immune system fights it
- Result | Acquired immunity
Notes
A vaccine trains the immune system to recognise and attack harmful germs, giving acquired immunity: protection developed after exposure to a pathogen or a vaccine.
Check yourself
A vaccine helps the body by...
Protection developed after exposure to a pathogen or a vaccine is called...
Why is the vaccinated child safe when the real germ arrives?
- training the immune system to recognise and attack harmful germs — correct. Yes. This is how a vaccine works.
- giving the body a new organ. A vaccine does not give an organ. It trains the immune system.
- making the body forget all germs. A vaccine trains the immune system to recognise germs.
- acquired immunity — correct. Yes. The body acquires the protection.
- a vector. A vector is an insect that carries pathogens.
- a deficiency. A deficiency is a lack of a nutrient.
- Its immune system was trained to recognise the germ — correct. Yes. It can attack the germ quickly.
- The real germ cannot enter any body. Germs can reach the body. The vaccine helps the immune system fight them.
- The germ is always too weak to do anything. The real germ can make an unvaccinated child ill.