Table 2.
Influenza-related parameter estimates used in the example analysis
| Parameter | Age group | References | ||
|---|---|---|---|---|
| 18–49 years | 50–64 years | 65–99 years | ||
| Annual per-person clinical influenza incidence in the absence of vaccination (all symptomatic cases) | 0.073 | 0.073 | 0.093 | Average over 9 seasons [27–29] |
| % of clinical cases requiring GP visit or outpatient treatmenta | 38.4% | 38.4% | 43.3% | Average over 9 seasons [27–29] |
| % of clinical cases requiring hospitalization | 0.7% | 0.7% | 4.9% | |
| % of clinical cases resulting in death | 0.009% | 0.134% | 1.17% | [6] |
| Costs (2018 US$)b | [6]; inflated from 2003 US$ to 2018 US$ using medical care component of CPI | |||
| Cost per GP visit/outpatient treatment | $343 | $548 | $579 | |
| Cost per hospitalization | $37,261 | $45,717 | $22,661 | |
| QALY losses | Derived from [22] | |||
| QALYs lost per influenza case | 0.0060 | 0.0063 | 0.0048 | |
| Incremental QALYs lost per hospitalized case | 0.0054 | 0.0052 | 0.0045 | |
CPI consumer price index, GP general practitioner, US$ United States dollars, QALY quality-adjusted life year
aCalculated as residual 1 minus the probability of hospitalization minus the probability of a non-medically attended case
bNo incremental costs are assigned to influenza-related deaths, to avoid double counting: the cost of death is assumed to be covered in the average cost estimates for outpatient treatment and hospitalization