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Vaccines for the 21st Century: A Tool for Decisionmaking (2000)

Chapter: Appendix 24: Streptococcus, Group A

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Suggested Citation:"Appendix 24: Streptococcus, Group A." Institute of Medicine. 2000. Vaccines for the 21st Century: A Tool for Decisionmaking. Washington, DC: The National Academies Press. doi: 10.17226/5501.
×

APPENDIX 24
Streptococcus, Group A

DISEASE BURDEN

Epidemiology

For the purposes of the calculations in this report, the committee estimated that there are 4,000,000 new cases of noninvasive Group A Streptococcus (GAS) per year in the United States. These cases were assumed to occur in people 24 years of age and under, with the highest incidence rate in children between the ages of 5 and 14 years. It was assumed that there was no mortality associated with noninvasive GAS disease. It was estimated that there, an additional 15,000 cases of invasive GAS disease and that the incidence rate of approximately 5.7 per 100,000 is the same in all age groups. It was assumed that 10% of invasive GAS disease is fatal. See Table A24–1.

Disease Scenarios

For the purposes of the calculation in this report, the committee assumed that 100% of noninvasive GAS infections result in a limited morbidity lasting 4 days and associated with a health utility index (HUI) of 0.9. The committee estimated that a small percentage of these patients (2,000) develop acute rheumatic fever and experience a more prolonged (28 days) illness associated with an HUI of .54. A very small number of those patients then go on to experience a chronic morbidity associated with an HUI of .82 for the duration of their lifetime.

See Appendix 28 for more information.

Suggested Citation:"Appendix 24: Streptococcus, Group A." Institute of Medicine. 2000. Vaccines for the 21st Century: A Tool for Decisionmaking. Washington, DC: The National Academies Press. doi: 10.17226/5501.
×

Table A24–1 Incidence Rate for Noninvasive and Invasive Group A Streptococcus Infections

Age Groups

Population

Incidence Rates (per 100,000)

Cases

NONINVASIVE INFECTIONS

<1

3,963,000

1,009.34

40,000

1–4

16,219,000

2,466.24

400,000

5–14

38,056,000

8,408.66

3,200,000

15–24

36,263,000

992.75

360,000

25–34

41,670,000

0.00

0

35–44

42,149,000

0.00

0

45–54

30,224,000

0.00

0

55–64

21,241,000

0.00

0

65–74

18,964,000

0.00

0

75–84

11,088,000

0.00

0

85+

3,598,000

0.00

0

Total

263,435,000

1,518.4

4,000,000

INVASIVE INFECTIONS

<1

3,963,000

5.69

226

1–4

16,219,000

5.69

924

5–14

38,056,000

5.69

2,167

15–24

36,263,000

5.69

2,065

25–34

41,670,000

5.69

2,373

35–44

42,149,000

5.69

2,400

45–54

30,224,000

5.69

1,721

55–64

21,241,000

5.69

1,209

65–74

18,964,000

5.69

1,080

75–84

11,088,000

5.69

631

85+

3,598,000

5.69

205

Total

263,435,000

5.69

15,000

For the purposes of this report, the committee assumed that invasive GAS disease manifests as necrotizing fasciitis (with and without lifetime sequelae) in 10% of cases and toxic shock (lasting 15 days and associated with HUIs of .16 during hospitalization and .58 following hospitalization) for 10% of cases. 80% of the invasive forms of the disease are associated with 2 weeks of illness and HUIs of .62 and .73 for the time spent inpatient and outpatient, respectively. See Table A24–2.

COST INCURRED BY DISEASE

Table A24–3 summarizes the health care costs incurred by GAS infections. For the purposes of the calculations in this report, it was assumed that all pa-

Suggested Citation:"Appendix 24: Streptococcus, Group A." Institute of Medicine. 2000. Vaccines for the 21st Century: A Tool for Decisionmaking. Washington, DC: The National Academies Press. doi: 10.17226/5501.
×

Table A24–2 Disease Scenarios for Group A Streptococcus Infection

 

No. of Cases

% of Cases

Committee HUI Values

Duration (years)

NONINVASIVE

 

Acute Infection

4,000,000

100.00%

0.90

0.0110 (4 days)

pharyngitis, skin infections, etc.

 

Acute Rheumatic Fever

2,000

0.05%

0.54

0.0767 (28 days)

Chronic Rheumatic Fever

100

0.0025%

0.82

25.6422 (discounted quality adjusted life expectancy at onset)

INVASIVE

 

Necrotizing Fasciitis: Severe

1,200

8.00%

 

ICU

 

0.16

0.0274 (10 days)

Post-ICU

 

0.45

0.0274 (10 days)

Necrotizing Fasciitis: Moderate

300

2.00%

0.51

0.0274 (10 days)

Necrotizing Fasciitis: Sequelae

1,050

7.00%

0.61

19.2128 (discounted quality adjusted life expectancy at onset)

Toxic Shock

1,500

10.00%

 

inpatient

 

0.16

0.0137 (5 days)

outpatient following hospitalization

 

0.58

0.0274 (10 days)

Other Invasive Forms

12,000

80.00%

 

inpatient

 

0.62

0.0192 (7 days)

outpatient after inpatient

 

0.73

0.0192 (7 days)

tients with acute, noninvasive GAS disease seek outpatient medical attention (physician, diagnostics, medication). It was also assumed that all patients experiencing acute rheumatic fever require hospitalization and associated costs. The small number of patients with chronic rheumatic disease require 2 physician visits per year for the duration of their lifetime.

For the purposes of this report, it was also assumed that all patients with fasciitis require hospitalization. The costs for severe fasciitis are approximately twice that for moderate fasciitis. Lifelong sequelae associated with necrotizing fasciitis were presumed to occur in most patients and were associated with yearly aftercare costs in approximately half of the patients.

Suggested Citation:"Appendix 24: Streptococcus, Group A." Institute of Medicine. 2000. Vaccines for the 21st Century: A Tool for Decisionmaking. Washington, DC: The National Academies Press. doi: 10.17226/5501.
×

Table 24–3 Health Care Costs Associated with Group A Streptococcus Infection

 

% with Care

Cost per Unit

Units per Case

Form of Treatment

Acute Infection

 

pharyngitis, skin infections, etc

100%

$150

1.0

outpatient treatment

Acute Rheumatic Fever

100%

$3,400

1.0

hospitalization

Chronic Rheumatic Fever

 

duration=life expectancy at onset

100%

$50

2.0

physician visit (2/year)

Necrotizing fasciitis: severe

100%

$7,000

1.0

hospitalization

 

100%

$150

1.0

physician c

Necrotizing fasciitis: moderate

 

hospitalization

100%

$3,000

1.0

hospitalization

 

100%

$150

1.0

physician c

Necrotizing fasciitis: sequelae

50%

$3,000

1.0

aftercare per year

Toxic shock

 

hospitalization

90%

$3,000

1.0

hospitalization

 

10%

$15,000

1.0

ventilator support

outpatient after hospitalization

100%

$250

1.0

physician b plus medication c

Other invasive forms

 

inpatient

100%

$4,000

1.0

hospitalization

outpatient after inpatient

100%

$250

1.0

physician b plus medication c

Patients with toxic shock from GAS were presumed to require hospitalization, with 10% requiring ventilator support and more expensive care. All patients with toxic shock were presumed to also require outpatient visits to a specialist and additional medication. Other forms of invasive disease were presumed to be associated with a hospitalization and subsequent outpatient visits to a specialist and additional medication.

VACCINE DEVELOPMENT

The committee assumed that it will take 15 years until licensure of a GAS vaccine and that $400 million needs to be invested. Table 4–1 summarizes vaccine development assumptions for all vaccines considered in this report.

Suggested Citation:"Appendix 24: Streptococcus, Group A." Institute of Medicine. 2000. Vaccines for the 21st Century: A Tool for Decisionmaking. Washington, DC: The National Academies Press. doi: 10.17226/5501.
×

VACCINE PROGRAM CONSIDERATIONS

Target Population

For the purposes of the calculations in this report, it is assumed that the target population for a GAS vaccine is all infants. It was assumed that 90% of the target population would utilize the vaccine.

Vaccine Schedule, Efficacy, and Costs

For the purposes of the calculations in this report, it was estimated that this vaccine would cost $50 per dose and that administration costs would be $10 per dose. Default assumptions of a 3-dose series and 75% effectiveness were accepted. Table 4–1 summarizes vaccine program assumptions for all vaccines considered in this report.

RESULTS

If a vaccine program for group A streptococci were implemented today and the vaccine were 100% efficacious and utilized by 100% of the target population, the annualized present value of the QALYs gained would be 16,500. Using committee assumptions of less-than-ideal efficacy and utilization and including time and monetary costs until a vaccine program is implemented, the annualized present value of the QALYs gained would be 6,200.

If a vaccine program for group A streptococci were implemented today and the vaccine was 100% efficacious and utilized by 100% of the target population, the annualized present value of the health care costs saved would be $495 million. Using committee assumptions of less-than-ideal efficacy and utilization and including time and monetary costs until a vaccine program is implemented, the annualized present value of the health care costs saved would be $185 million.

If a vaccine program for group A streptococci were implemented today and the vaccine was 100% efficacious and utilized by 100% of the target population, the annualized present value of the program cost would be $720 million. Using committee assumptions of less-than-ideal efficacy and utilization and including time and monetary costs until a vaccine program is implemented, the annualized present value of the program cost would be $360 million.

Using committee assumptions of time and costs until licensure, the fixed cost of vaccine development has been amortized and is $12 million for a group A streptococci vaccine.

Suggested Citation:"Appendix 24: Streptococcus, Group A." Institute of Medicine. 2000. Vaccines for the 21st Century: A Tool for Decisionmaking. Washington, DC: The National Academies Press. doi: 10.17226/5501.
×

If a vaccine program were implemented today and the vaccine was 100% efficacious and utilized by 100% of the target population, the annualized present value of the cost per QALY gained is $14,000. Using committee assumptions of less-than-ideal utilization and including time and monetary costs until a vaccine program is implemented, the annualized present value of the cost per QALY gained is $30,000.

See Chapters 4 and 5 for details on the methods and assumptions used by the committee for the results reported.

READING LIST

Bisno AL. Streptococcus Pyogenes. In: Principles and Practice of Infectious Diseases. GL Mandell, JE Bennett, Dolin R eds. New York, NY: Churchill Livingstone, 1995, pp. 1786–1799.


Kaplan EL. Group A Streptococcal Infections. In: Textbook of Pediatric Infectious Diseases. RD Feigin and JD Cherry eds. Philadelphia, PA: WB Saunder Company, 1992, pp. 1296–1305.

Suggested Citation:"Appendix 24: Streptococcus, Group A." Institute of Medicine. 2000. Vaccines for the 21st Century: A Tool for Decisionmaking. Washington, DC: The National Academies Press. doi: 10.17226/5501.
×
Page 299
Suggested Citation:"Appendix 24: Streptococcus, Group A." Institute of Medicine. 2000. Vaccines for the 21st Century: A Tool for Decisionmaking. Washington, DC: The National Academies Press. doi: 10.17226/5501.
×
Page 300
Suggested Citation:"Appendix 24: Streptococcus, Group A." Institute of Medicine. 2000. Vaccines for the 21st Century: A Tool for Decisionmaking. Washington, DC: The National Academies Press. doi: 10.17226/5501.
×
Page 301
Suggested Citation:"Appendix 24: Streptococcus, Group A." Institute of Medicine. 2000. Vaccines for the 21st Century: A Tool for Decisionmaking. Washington, DC: The National Academies Press. doi: 10.17226/5501.
×
Page 302
Suggested Citation:"Appendix 24: Streptococcus, Group A." Institute of Medicine. 2000. Vaccines for the 21st Century: A Tool for Decisionmaking. Washington, DC: The National Academies Press. doi: 10.17226/5501.
×
Page 303
Suggested Citation:"Appendix 24: Streptococcus, Group A." Institute of Medicine. 2000. Vaccines for the 21st Century: A Tool for Decisionmaking. Washington, DC: The National Academies Press. doi: 10.17226/5501.
×
Page 304
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Vaccines have made it possible to eradicate the scourge of smallpox, promise the same for polio, and have profoundly reduced the threat posed by other diseases such as whooping cough, measles, and meningitis.

What is next? There are many pathogens, autoimmune diseases, and cancers that may be promising targets for vaccine research and development.

This volume provides an analytic framework and quantitative model for evaluating disease conditions that can be applied by those setting priorities for vaccine development over the coming decades. The committee describes an approach for comparing potential new vaccines based on their impact on morbidity and mortality and on the costs of both health care and vaccine development. The book examines:

  • Lessons to be learned from the polio experience.
  • Scientific advances that set the stage for new vaccines.
  • Factors that affect how vaccines are used in the population.
  • Value judgments and ethical questions raised by comparison of health needs and benefits.

The committee provides a way to compare different forms of illness and set vaccine priorities without assigning a monetary value to lives. Their recommendations will be important to anyone involved in science policy and public health planning: policymakers, regulators, health care providers, vaccine manufacturers, and researchers.

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