Making a safe vaccine

The idea

Vaccines are made from weakened or dead pathogens or from inactive or harmless parts of a pathogen; some newer vaccines instruct body cells to make a harmless part of the germ for the immune system to learn to fight.

Teach, but do not harm

A vaccine must show the immune system a germ without making you ill. How can a harmful germ be made safe to use?

What would make a germ safe?

• Weaken it, kill it, or use only a harmless part
• Use it at full strength
• Make it bigger

Make it safe

Start from a harmful germ. Tap each way to make a safe vaccine.

Ways to make vaccines

Vaccines are made from weakened or dead pathogens, or from inactive or harmless parts of a pathogen. Some newer vaccines instruct our body cells to make a harmless part of the germ, which the immune system then learns to fight.

Example from the book: a tetanus shot has an inactivated bacterial toxin. It helps the immune system develop protection without causing the disease.

• Way | What it uses
• Weakened pathogen | A germ made weak
• Dead pathogen | A germ that is dead
• Inactive or harmless part | Only a piece of the germ
• Newer vaccines | Instructions for our cells to make a harmless part

Notes

Vaccines come from weakened or dead pathogens, or inactive or harmless parts of a pathogen. Some newer ones instruct body cells to make a harmless part of the germ.

Check yourself

Which of these can be used to make a vaccine?

Some newer vaccines instruct our own body cells to make...

Why must vaccine ingredients be weakened, dead or harmless?

• A weakened or dead pathogen — correct. Yes. It cannot cause the disease, but the immune system can learn from it.
• A fully active pathogen. A fully active pathogen would cause the disease.
• An antibiotic. An antibiotic is a medicine against bacteria. Vaccines are made from pathogens or parts of them.
• a harmless part of the germ — correct. Yes. The immune system then learns to fight it.
• the whole active germ. That would make us ill. The cells make only a harmless part.
• an antibiotic. The cells make a harmless part of the germ, not an antibiotic.
• So they can train the immune system without causing the disease — correct. Yes. A vaccine should not make us ill.
• So they can cure a disease the person already has. Vaccines are preventive, not curative. You will see this next.
• So the vaccine can work as an antibiotic. A vaccine trains the immune system. It is not an antibiotic.