Table 2 Key model parameter distributions

Proportion of high-risk groups

Additional file 4: Fig. S3

Beta

Flu-related ILI consultation rate [28]

Additional file 5: Table S2

Normal

 Beijing (2013–2014)

105 (95%CI 85–129)

Normal with μ = 105, sd = 11.22

 Beijing (2014–2015)

66 (95%CI 50–86)

Normal with μ = 66, sd = 9.18

 Jingzhou, Hubei province (2011–2012)

89 (95%CI 85–90)

Uniform (min = 85/100,000, max = 90/100,000)

Flu-related respiratory excess mortality [12]

Additional file 5: Table S2

Lognormal

 Probability of no-healthcare-use

Urban 9.7,

Urban: Dirichlet with α1 = 107, α2 = 704, α3 = 269,

Rural: Dirichlet with α1 = 43, α2 = 394, α3 = 62

Rural 8.6

 Probability of self-treatment, seeking care in Community/Township Health Service Centers

Urban 66.0,

Rural 79.0

 Probability of visiting doctors in county-level and above hospitals

Urban 24.3

Rural 12.4

Odds ratio of influenza-related hospitalization in high-risk groups compared to low-risk groups [29]

3.39

Lognormal with μ = 1.22, sd = 0.14

Odds ratio of influenza-related death in high-risk groups compared to low-risk groups [29]

2.04

Lognormal with μ = 0.71, sd = 0.08

Vaccine cost (US$ in 2013) [14]

5.73 (95%UI 5.43–6.03)

Bootstrap from data on influenza vaccine cost

Influenza outpatients visits and hospitalization costs (US$ in 2013) [32]

Outpatients: 129 (95%UI 75–156)

Bootstrap from data on national retrospective survey

Inpatients: 2735 (95%UI 1401–4482)

Duration of influenza episode for outpatients and inpatients (days) [37]

Outpatients: 6.2 (SD 2.2)

Bootstrap from data on national retrospective survey

Inpatients: 16.0 (SD 10.7)

Utility of influenza outpatients and inpatients [37]

Outpatients: 0.5733 (95%UI 0.4650–0.6608)

Bootstrap from data on national retrospective survey

Inpatients: 0.4128 (95%UI 0.1793–0.6380)

Background health utility [38]

Urban

60–74 years: 0.8071 (SD 0.0039);

≥ 75 years: 0.7719 (SD 0.0093)

Rural

60–74 years: 0.7434 (SD 0.0031);

≥ 75 years: 0.6943 (SD 0.0078)

Normal distribution

Risk of infected from influenza in vaccinated group vs. unvaccinated group (odds ratio) [44]

0.64 (0.52–0.78)

Lognormal with μ = − 0.45, sd = 0.10