Flashcards · Biology · Human Defences and Immunity
Herd Immunity and Evaluating Vaccination
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What is herd immunity?
The protection of unvaccinated people, because so many others are immune that the disease cannot spread.
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Who depends on herd immunity?
Babies, people with weak immune systems, and those the vaccine does not work for.
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What proportion must be immune for measles herd immunity?
About 95%.
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What happens if vaccination rates fall below the threshold?
Outbreaks can happen again.
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Give one advantage of vaccination.
It prevents serious disease and saves lives.
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Give one disadvantage of vaccination.
Mild side effects, or it does not work for everyone.
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What is a common side effect of vaccines?
Soreness, redness or a slight fever.
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Is any vaccine 100% effective?
No.
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What was the MMR scare?
A false claim in 1998 that the MMR vaccine caused autism.
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What happened to MMR uptake after the scare?
It fell, and measles outbreaks followed.
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Why was Wakefield's paper retracted?
The research was flawed and unethical.
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Which disease has been eradicated by vaccination?
Smallpox.
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Why is the cost of vaccination worthwhile?
It is less than the cost of treating the disease.
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Why can the flu vaccine be less effective some years?
The virus mutates, so the vaccine may not match.
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Why is a high uptake important?
To keep the proportion immune above the herd immunity threshold.
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Common mistake about herd immunity?
Saying that unvaccinated people are immune. They are protected only because the disease cannot spread to them.