Fatality (%) also called the Case Fatality Rate

The Case Fatality (%) tells us what percent of people who have a specific disease die as a result of their specific disease.

1.The following table is actual Covid-19 data from a large public health department. Data is from March 2020 to present. Use this table to answer the following questions.

Age Group

Cases

Deceased

0-4

2125

1

5-9

2068

0

10-14

3081

0

15-19

5890

0

20-24

7967

0

25-29

7776

0

30-34

7246

7

35-39

6419

6

40-44

6220

13

45-49

6010

21

50-54

6055

34

55-59

5906

49

60-64

5223

95

65-69

3833

120

70-74

3022

194

75-79

1941

168

80-84

1394

189

85 and older

1893

434

* Age group is in years

a.What is the Case Fatality (%) for people aged 20-24 years?

b.What is the Case Fatality (%) for people aged 80-84 years?

c.Given this table, does age appear to be positively associated with Covid-19 mortality? Stated another way - does Covid-19 mortality increase as age increases? Please explain your answer.

2.The following table provides a detailed listing of cases based on an outbreak investigation of an outbreak of acute gastroenteritis following a church supper in Oswego County, New York. Of the 80 people who reported being present, 46 suffered an acute illness characterized by nausea, vomiting, diarrhea and abdominal pain, with an incubation period ranging from 3 to 7 hours. Interviews were possible with 75 of the people present at the supper and detailed information was obtained regarding occurrence of symptoms, time of onset, and food consumed at the supper.

Case Listing, Outbreak Investigation of Acute Gastroenteritis, Oswego County, NY

Food Item

Intake of Food Item

No Intake of Food Item

# Sick

Total

Attack Rate

# Sick

Total

Attack Rate

Baked Ham

29

46

63

17

29

59

Spinach

26

43

60

20

32

63

Mashed Potato

23

37

62

23

38

52

Cabbage Salad

18

28

64

28

47

60

Jell-O

16

23

70

30

52

58

Rolls

21

37

57

25

38

66

Brown Bread

18

27

67

28

48

58

Milk

2

4

50

44

71

62

Coffee

19

31

61

27

44

61

Water

13

24

54

33

51

65

Cakes

27

40

67

19

35

54

Vanilla Ice Cream

43

54

80

3

21

14

Chocolate Ice Cream

25

47

53

21

28

74

Fruit Salad

4

6

67

42

69

61

* Calculation of Attack Rate: (# Sick) / (Total) * 100;Attack rates have been rounded to the nearest whole number.

a.How would you handle data from people who cannot recall whether or not a particular food was eaten?

b.Which food above is the most likely to have caused the illness? Please explain your answer.

3.Complete the table below, by calculating the attack rate ratio for each food item. You do not need to show your work for this homework problem.

If the Attack Rate Ratio is greater than 1.0, then there is a positive association between the food item and the illness (i.e. the food item may cause the illness). If the Attack Rate Ratio is less than 1.0, then there is a negative association between the food item and the illness.

Food Item

Intake: Attack Rate

No Intake: Attack Rate

Attack Rate Ratio

Baked Ham

63

59

Spinach

60

63

Mashed Potato

62

52

Cabbage Salad

64

60

Jell-O

70

58

Rolls

57

66

Brown Bread

67

58

Milk

50

62

Coffee

61

61

Water

54

65

Cakes

67

54

Vanilla Ice Cream

80

14

Chocolate Ice Cream

53

74

Fruit Salad

67

61

a.Which food item has the strongest negative association with the illness? What do you think explains this?

b.Suppose that 2 food items appeared to have been associated with illness. How might you explain this? What would you do for further analysis?

c.After incriminating a food numerically, as above, what further steps would be necessary to prove that it was the source?