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Vaccines for the 21st Century: A Tool for Decisionmaking
APPENDIX 20
Respiratory Syncytial Virus
DISEASE BURDEN
Epidemiology
For the purposes of the calculations in this report, the committee estimated that there are approximately 5 million infections with respiratory syncytial virus (RSV) each year in the United States. It was assumed that 1 million RSV infections occur in children under 1 year of age, 2 million RSV infections in children between the ages of 1 and 4 years of age, and 2 million RSV infections in people 5 years of age and greater. The number of deaths due to RSV infection in those three age groups is 300, 200, and 20, respectively. The mortality in the third age group is seen in those 65 years of age and older. See Table A20–1.
Disease Scenarios
For the purposes of the calculation in this report, the committee described disease states associated with RSV infection as either a mild upper respiratory or related condition (pharyngitis/otitis media) or as bronchiolitis/pneumonia. It was assumed that in children 4 years of age and under the relative distribution of cases between those two scenarios is 60% and 40% respectively. In people 5 years of age and older, it was assumed that 80% of infections manifest as pharyngitis/otitis media and 20% as the more severe lower respiratory disease. The health utility index (HUI) and time in that state range from 7 days at an HUI of .9 (pharyngitis) to 7 days at an HUI of .5 (inpatient treatment of bronchiolitis/pneumonia). See Table A20–2.
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Table A20–1 Incidence Rate for Respiratory Syncytial Virus Infection
Age Groups
Population
Incidence Rates (per 100,000)
Cases
<1
3,963,000
25,233.41
1,000,000
1–4
16,219,000
12331.22
2,000,000
5–14
38,056,000
822.19
312,892
15–24
36,263,000
822.19
298,150
25–34
41,670,000
822.19
342,606
35–44
42,149,000
822.19
346,545
45–54
30,224,000
822.19
248,498
55–64
21,241,000
822.19
174,641
65–74
18,964,000
822.19
155,920
75–84
11,088,000
822.19
91,164
85+
3,598,000
822.19
29,582
Total
263,435,000
COST INCURRED BY DISEASE
Table A20–3 summarizes the health care costs incurred by RSV infections. For the purposes of the calculations in this report, it was assumed that treatment of pharyngitis and otitis media are associated with physician visit, diagnostic, and medication (over-the-counter, symptomatic treatment). It was estimated that 100% of children 4 years of age and under incur such treatment but that approximately 50% of people 5 years of age and older seek such medical treatment.
It was assumed that the majority of cases of lower respiratory infections are treated as an outpatient and involve costs similar to that for pharyngitis, but with the addition of an extra physician visit. For the small number of cases of lower respiratory disease which is treated as an inpatient, hospitalization costs are added to the costs similar to that incurred as outpatient treatment. It was assumed that while 100% of children 4 years of age and under receive treatment for lower respiratory infections, only 50% of people 5 years of age or older who are not hospitalized for lower respiratory RSV infections seek medical treatment.
VACCINE DEVELOPMENT
The committee assumed that it will take 7 years until licensure of a RSV vaccine and that $360 million needs to be invested. It was assumed that the same vaccine would be used in infants and in adolescent girls. Table 4–1 summarizes vaccine development assumptions for all vaccines considered in this report.
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Table A20–2 Disease Scenarios for RSV
No. of Cases
% of Cases
Committee HUI Values
Duration (years)
AGE<1
Total Deaths
300
Total Cases
1,000,000
Upper Respiratory
pharyngitis, otitis media
600,000
60.00%
0.90
0.0192 (7 days)
Bronchiolitis/pneumonia
outpatient only
340,000
34.00%
0.75
0.0274 (10 days)
Bronchiolitis/pneumonia
60,000
6.00%
inpatient
0.50
0.0192 (7 days)
outpatient
0.75
0.0082 (3 days)
AGE 1–4
Total Deaths (from acute infection)
200
Total Cases
2,000,000
Upper Respiratory
pharyngitis, otitis media
1,200,000
60.00%
0.90
0.0192 (7 days)
Bronchiolitis/pneumonia
outpatient only
760,000
38.00%
0.75
0.0274 (10 days)
Bronchiolitis/pneumonia
40,000
2.00%
inpatient
0.50
0.0192 (7 days)
outpatient
0.75
0.0082 (3 days)
AGE 5+
Total Deaths (from acute infection)
20
Total Cases
2,000,000
Upper Respiratory
pharyngitis, otitis media
1,600,000
80.00%
0.90
0.0192 (7 days)
Bronchiolitis/pneumonia
outpatient only
396,000
19.80%
0.75
0.0274 (10 days)
Bronchiolitis/pneumonia
4,000
0.20%
inpatient
0.50
0.0192 (7 days)
outpatient
0.75
0.0082 (7 days)
VACCINE PROGRAM CONSIDERATIONS
Target Population
For the purposes of the calculations in this report, it is assumed that the target population for this vaccine is all adolescent girls (age 12 years) and all infants. For this example, the committee included adolescent girls in order to induce immunity that would protect the neonate. Infants are immunized to protect against disease after 1 year of age. It was assumed that 50% of adolescent females and 90% of infants would utilize the vaccine.
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Table 20–3 Health Care Costs Associated with RSV Infections
% with Care
Cost per Unit
Units per Case
Form of Treatment
AGE<5
Upper Respiratory
pharyngitis, otitis media
100%
$50
1.0
physician a
100%
$50
1.0
diagnostic a
100%
$50
1.0
medication b
Bronchiolitis/pneumonia
outpatient only
100%
$50
1.0
physician a
100%
$50
1.0
diagnostic a
100%
$50
1.0
medication b
Bronchiolitis/pneumonia
inpatient
100%
$4,000
1.0
hospitalization
100%
$50
2.0
physician a
100%
$50
1.0
diagnostic a
100%
$50
1.0
medication b
AGE 5+
Upper Respiratory
pharyngitis, otitis media
100%
$50
1.0
physician a
100%
$50
1.0
diagnostic a
100%
$50
1.0
medication b
Bronchiolitis/pneumonia
outpatient only
100%
$50
1.0
physician a
100%
$50
1.0
diagnostic a
100%
$50
1.0
medication b
Bronchiolitis/pneumonia
inpatient
100%
$4,000
1.0
hospitalization
100%
$50
2.0
physician a
100%
$50
1.0
diagnostic a
100%
$50
1.0
medication b
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 RSV 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 33,000. Using committee assumptions of less-than-ideal efficacy and utilization and including time and monetary costs until a vaccine program is implemented, the annualized
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present value of the QALYs gained would be 14,000. Slightly over half of the loss is accounted for by disease in children under 1 year of age. Deaths of very young infants contribute substantially to loss of QALYs.
If a vaccine program for RSV 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 $1.15 billion. 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 $490 million.
If a vaccine program for RSV 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 $1.05 billion. 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 $570 million.
Using committee assumptions of time and costs until licensure, the fixed cost of vaccine development has been amortized and is $10.8 million for a RSV vaccine.
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 -$3,000. A negative value represents a saving in costs in addition to a saving in QALYs. 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 $6,500.
See Chapters 4 and 5 for details on the methods and assumptions used by the committee for the results reported.
READING LIST
CDC. Update: Respiratory Syncytial Virus Activity—United States, 1996–7 Season. Morbidity and Mortality Weekly Report 1996; 45:1053–1055.
Committee on Infectious Diseases and Committee on Fetus and Newborn of the American Academy of Pediatrics. Respiratory Syncytial Virus Immune Globulin Intravenous: Indications for Use. Pediatrics 1997; 99:645–650.
Dowell SF, Anderson LJ, Gary HE, et al. Respiratory Syncytial Virus Is an Important Cause of Community-Acquired Lower Respiratory Infection among Hospitalized Adults. The Journal of Infectious Diseases 1996; 174:456–462.
Fisher RG, Gruber WC, Edwards KM, et al. Twenty Years of Outpatient Respiratory Syncytial Virus. Pediatrics 1997; 99:E7.
Hall CB. Respiratory Syncytial Virus. In: Textbook of Pediatric Infectious Diseases. RD Feigin and JD Cherry eds. Philadelphia, PA: WB Saunder Company, 1992, pp. 1633–1656.
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Hall CB, McCarthy CA. Respiratory Syncytial Virus. In: Principles and Practice of Infectious Diseases. GL Mandell, JE Bennett, Dolin R eds. New York, NY: Churchill Livingstone, 1995, pp. 1501–1519.
Meissner HC, Groothuis JR. Immunoprophylaxis and the Control of RSV Disease. Pediatrics 1997; 100:260–263.
Paradise JL, Rockette HE, Colborn DK, et al. Otitis Media in 2253 Pittsburgh-Area Infants: Prevalence and Risk Factors During the First Two Years of Life. Pediatrics 1997; 99:318–333.
Prober CG, Wang EEL. Reducing the Morbidity of Lower Respiratory Tract Infections Caused by Respiratory Syncytial Virus: Still No Answer. Pediatrics 1997; 99:472–475.
Rodriguez WJ, Gruber WC, Welliver RC, et al. Respiratory Syncytial Virus (RSV) Immune Globulin Intravenous Therapy for RSV Lower Respiratory Tract Infection in Infants and Young Children at High Risk for Severe RSV Infections. Pediatrics 1997; 99:454–461.
Ventura SJ, Martin JA, Mathews TJ, et al. Advance Report of Final Natality Statistics, 1994. Monthly Vital Statistics Report 1996; 44.
Representative terms from entire chapter:
vaccine program
