CAIE A Level Biology 9700 · Immunity
A study compared the incidence of a infectious disease, 'Zythia', in two towns over one year. Town A had 95% of its population vaccinated against Zythia, while Town B had only 45% vaccinated. The number of confirmed Zythia cases during the year was:
| Town | Vaccination coverage | Number of cases |
|---|---|---|
| A | 95% | 12 |
| B | 45% | 450 |
Explain how vaccination programmes can help control the spread of infectious diseases like Zythia, using the data in the table to support your answer.
5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
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