Advantages and disadvantages of immunisationSpec 5.15B
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.
Quick check
Name two physical barriers in the human body.
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Any two of: skin, mucus, cilia.
What do lysozymes do?
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They are enzymes that break down the cell walls of bacteria.
What is an antigen?
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A molecule, usually on the surface of a pathogen, that triggers an immune response.
Why is the secondary response better than the primary response?
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Memory lymphocytes make it faster and produce more antibodies.
Triple only: what is herd immunity?
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When a large proportion of the population is immune, so the pathogen cannot spread easily and non-immune people are protected.