Advantages and disadvantages of immunisationSpec 5.15B
In short
Immunisation protects people from serious diseases, reduces the spread of disease and can prevent epidemics. Through herd immunity, when a large proportion of a population is immune, it also protects people who cannot be vaccinated. Disadvantages are that some people have side effects, it does not always work, boosters may be needed and some pathogens change often.
In a discuss question you must give both sides. Use the ideas below.
| Advantages | Disadvantages |
|---|---|
| Protects the person from serious diseases | Some people have side effects, such as a sore arm or fever; very rarely, serious reactions happen |
| Reduces the spread of disease, so epidemics can be prevented | It does not always work, and some people are still infected |
| Some diseases have been almost wiped out | Boosters may be needed to keep protection high |
| Protects people who cannot be vaccinated, through herd immunity | Some pathogens change often, so new vaccines are needed |
Herd immunity
Herd immunity happens when a large proportion of a population is immune to a disease. The pathogen finds it hard to spread because most people it reaches are immune. This also protects the few who are not immune, such as babies who are too young to be vaccinated or people whose immune system is weak.
If fewer people are vaccinated, herd immunity is lost and the disease can spread through the population again.
End a discuss answer with a short judgement, for example that the benefits outweigh the risks for most people, and say why.
Quick check
Name two physical barriers in the human body.
Show answer
Any two of: skin, mucus, cilia.
What do lysozymes do?
Show answer
They are enzymes that break down the cell walls of bacteria.
What is an antigen?
Show answer
A molecule, usually on the surface of a pathogen, that triggers an immune response.
Why is the secondary response better than the primary response?
Show answer
Memory lymphocytes make it faster and produce more antibodies.
Triple only: what is herd immunity?
Show answer
When a large proportion of the population is immune, so the pathogen cannot spread easily and non-immune people are protected.
Written and checked against the Edexcel GCSE Biology (1BI0) specification · Updated October 2026