Case-Control Calculation Enter only numeric values into the answer line. Place a
ID: 78844 • Letter: C
Question
Case-Control Calculation Enter only numeric values into the answer line. Place a leading 0 before the decimal and remember to round to two decimal places. Note your answers for the next short essay question. Swine Influenza (SI) is a growing concern at the local Broncoville Health Department in Lawrence, Kansas. You are working for a pharmaceutical company which is developing a human vaccine against SI. You are in charge of testing the vaccine’s effectiveness. You need to determine if one or two doses of vaccine is required to provide immunity. You field test and collect the following information about the vaccine status of persons who did and did not contract SI after getting either one or two doses of vaccine. Develop a 2 x 2 table with the following information: Of the 727 cases of SI, 203 received two doses of vaccine. Of 1,239 controls, 771 received two doses of vaccine for SI. What is the likelihood of contracting SI with only one dose of vaccine?
1. Calculate the incidence of persons with one dose of vaccine for SI
2. Calculate the incidence of persons with two doses of vaccine for SI
3. Calculate the odds ratio of developing SI among those with one dose of vaccine for SI
Explanation / Answer
There are 727 cases. Out of them 203 received two doses of vaccine. 727-203=524 received one dose
There are 1239 controls. Out of them 771 received two doses of vaccine. 1239-771=468 received one dose.
Cases
Controls
Total
One dose
524
468
992
two doses
203
771
974
Total
727
1239
1966
Incidence of persons with one dose of vaccine for SI is 524/992 = 0.52822580645
Incidence of persons with two doses of vaccine for SI is 203/974 = 0.20841889117
Odds ratio of developing SI:
Odds of SI in one dose group are 524/468 = 1.11965811966
Odds of SI in two doses group are 203/771 = 0.26329442282
Odds ratio is 1.11965811966/0.26329442282 = 4.25249463193
Cases
Controls
Total
One dose
524
468
992
two doses
203
771
974
Total
727
1239
1966