Gce Model Questions Vol1 2017 Biology Question 19

Practice objective / multiple choice question 19 from the 2017 Gce Model Questions Vol1 Biology examination.

Gce Model Questions Vol1 2017 Biology Objective / Multiple Choice Hard Difficulty
Question 19 GCE_MODEL_QUESTIONS_VOL1 • 2017 • BIOLOGY • objective

A novel viral infection has a basic reproduction number \(R_{0}=3.5\). A vaccine is 80 % effective at preventing infection. (a) Calculate the theoretical herd‑immunity threshold (the proportion of the population that must be immune) assuming perfect immunity. (b) Taking the vaccine efficacy into account, determine the minimum proportion of the total population that must be vaccinated to achieve herd immunity. (c) In a population of 2 million, 10 % are already immune due to prior infection. How many additional individuals need to be vaccinated to reach herd immunity?

Answer Options

Correct Answer A. (a) 71.4 %; (b) about 89.3 % of the population must be vaccinated; (c) roughly 1.54 × 10⁶ additional individuals need vaccination.
B. (a) 75.0 %; (b) about 88.0 % of the population must be vaccinated; (c) roughly 1.45 × 10⁶ additional individuals need vaccination.
C. (a) 68.6 %; (b) about 85.0 % of the population must be vaccinated; (c) roughly 1.30 × 10⁶ additional individuals need vaccination.
D. (a) 71.4 %; (b) about 92.0 % of the population must be vaccinated; (c) roughly 1.60 × 10⁶ additional individuals need vaccination.
Correct Answer
A
Correct Option:
(a) 71.4 %; (b) about 89.3 % of the population must be vaccinated; (c) roughly 1.54 × 10⁶ additional individuals need vaccination.

About This Question

This is Gce Model Questions Vol1 2017 Biology Question 19. It is one of the objective questions from the 2017 Gce Model Questions Vol1 Biology examination.

Difficulty level: Hard .

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