Igcse Model Questions Vol1 2022 Biology Question 19
Practice objective / multiple choice question 19 from the 2022 Igcse Model Questions Vol1 Biology examination.
In a community of 30 000 people, a vaccine trial recorded 300 cases of disease X among 15 000 unvaccinated individuals and 75 cases among 15 000 vaccinated individuals over one year.\n\n(a) Calculate the vaccine efficacy as a percentage reduction in incidence.\n(b) How many people must be vaccinated to prevent at least 200 cases per year, assuming the same efficacy and that the disease incidence in the unvaccinated population remains as observed? Round up to the nearest whole person.
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This is Igcse Model Questions Vol1 2022 Biology Question 19. It is one of the objective questions from the 2022 Igcse Model Questions Vol1 Biology examination.
Difficulty level: Hard .
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