Vaccine for Malaria In order for a vaccine to be effective, it should reduce a p
ID: 3273473 • Letter: V
Question
Vaccine for Malaria In order for a vaccine to be effective, it should reduce a person's chance of acquiring a disease. Consider a hypothetical vaccine for malaria-a tropical disease that kills between 1.5 and 2.7 milion people every year.^20 Suppose the vaccine is tested with 500 volunteers in a village who are malaria free at the beginning of the trial. Two hundred of the volunteers will get the experimental vaccine and the rest will not be vaccinated. Suppose that the chance of contracting malaria is 10% for those who are not vaccinated. Construct a two-way table to show the results of the experiment if: (a) The vaccine has no effect. b) The vaccine cuts the risk of contracting malaria in half.Explanation / Answer
(a) The vaccination has no effect:
Contacting malaria Not contacting malaria Total
Vaccinated 100 100 200
Not vaccinated 30 270 300
Total 130 370 500
EXPLANATION: Total Vluntees = 500. Out of this, 200 are vaccinated. Since vaccination has no effect, Contacting malaria = Not contactmalaria = 100. In Not vaccinated, 10% are contacting malaia. That number is therefore 30.
(b) The vaccination cuts the risk of contacting malaria in half:
Contacting malaria Not contacting malaria Total
Vaccinated 50 150 200
Not vaccinated 30 270 300
Total 80 420 500
EXPLANATION: Since vaccination cuts the risk of mlaria in half: For vaccinaed: Contacting malaria is reduced to 50.
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