Table 1.
Epidemiological and Economic Parameters, Baseline Values, Distribution, and Associated References
| Model parameter | Baseline value | Distribution | Ref |
|---|---|---|---|
| Transmission probability per contact in age group k, βk | 0.1162 for k=1, 2 | – | 18 |
| 0.0743 for k=3 | |||
| 0.0324 for k=4 | |||
| 0.0294 for k=5 | |||
| 0.0300 for k=6 | |||
|
| |||
| Rate of LAIV vaccination in age group k at time t, Ψk(t) | Fit to the current vaccine coverage data (Appendix Figure 2) | – | 23 |
|
| |||
| Rate of IIV vaccination in age group k at time t, θk(t) | Fit to the current vaccine coverage data (Appendix Figure 2) | – | 23 |
|
| |||
| Relative reduction in risk of infection among the vaccinated compared to the unvaccinated (LAIV), σk | 0.82 for VE of 83% | – | 3,24, 6 |
| 0 (2014-15 only) | |||
|
| |||
| Relative reduction in risk of infection among the vaccinated compared to the unvaccinated (IIV), ωk | 0.63 for VE of 64% | – | 3,24, 6 |
| 0.13 for VE of 15% (2014-15 only) | |||
|
| |||
| Latency period (days), 1/h | 1.2 | – | 14 |
|
| |||
| Proportion of infected people who become symptomatic, p | 0.67 | – | 15 |
|
| |||
| Relative infectiousness of asymptomatic infection compared to symptomatic ones, b | 0.5 | – | 16 |
|
| |||
| Infectious period (days), 1/γ | 4.5 | – | 14 |
|
| |||
| Influenza-related death rate, α2 | 2.3114 × 10-5 | Triangular (1.1557×10-5 – 3.4671×10-5) | 31 |
|
| |||
| Breakdown of symptomatic influenza | 30 | ||
| Uncomplicated influenza | 69% | – | |
| Complicated influenza | |||
| Influenza + AOM | 11% | – | |
| Influenza + LRI + (AOM) | 20% | – | |
|
| |||
| Probability of influenza-related events | |||
| OTC medication, conditional on symptomatic influenza | 0.433 | Triangular (0.217 – 0.650) | 31 |
| Outpatient visit, conditional on symptomatic influenza | 0.35 | Triangular (0.175 – 0.525) | 7 |
| Hospitalization, conditional on symptomatic influenza | 0.0053 | Triangular (0.0027 – 0.0080) | 7,9 |
| Death (LR and HR (10%) weighted average), conditional on symptomatic influenza | 2.3114 × 10-5 | Triangular (1.1557×10-5 – 3.4671×10-5) | 31 |
|
| |||
| LAIV-associated adverse events (%) | 30 | ||
| MSW | 2.10 | Beta (α=47, β=2140) | |
| Reactogenicity event | |||
| Injection site event | 35.4 | – | |
| 16.7 | – | ||
|
| |||
| IIV-associated adverse events (%) | 30 | ||
| MSW | 2.33 | Beta (α=56, β=2347) | |
| Reactogenicity event | |||
| Injection site event | 24.8 | – | |
| 24.1 | – | ||
|
| |||
| Unit costs for children 2-8 years of age | |||
|
| |||
| Vaccine-related costs (per dose) | 3,28 | ||
| LAIV | $23.42 | – | |
| IIV | $14.61 | Triangular (13.05 – 18.27) | |
| Administration of LAIV | $12.92 | – | |
| Administration of IIV | $12.92 | – | |
|
| |||
| Adverse event-related costs (per episode) | 3 | ||
| MSW | $82.10 | Triangular (81.50 – 82.71) | |
| Reactogenicity event | |||
| Injection site event | $2.36 | – | |
| $2.36 | – | ||
|
| |||
| Influenza-related direct costs | |||
| Hospitalization for influenza | $5850 | Triangular (2372 – 10,760) | 31, 31 |
| Outpatient visit (including prescription medication) | $145 | Triangular (133 – 170) | 31 |
| OTC medication | $6.23 | – | |
|
| |||
| Direct non-medical costs | |||
| Transportation costs | $7.50 | – | 3 |
|
| |||
| Indirect costs | |||
| Cost of caregiver work loss per influenza illness | $178 | – | 31 |
|
| |||
| Health state utilities and durations | |||
|
| |||
| Health state utility | 3 | ||
| Non influenza; no wheezing | 0.933 | – | |
| MSW | 0.851 | – | |
| Influenza (uncomplicated and complicated) | 0.558 | – | |
|
| |||
| Average number of febrile days | 3 | ||
| Uncomplicated influenza | 3.00 | – | |
| Influenza + AOM | 3.52 | – | |
| Influenza + LRI | 3.33 | – | |
|
| |||
| Average number of symptom days | 3 | ||
| MSW | 12.78 | – | |
LAIV, live attenuated influenza vaccine; IIV, inactivated influenza vaccine; AOM, acute otitis media; LRI, lower respiratory tract infection; LR, low risk; HR, high risk; OTC, over-the-counter; MSW, medically significant wheezing