Table 1.

Model parameters and sources of data for estimating the burden of seasonal influenza, Beijing, 2015–2016 season

Parameters	Sources of data	Data included in the model
Na: age-specific reported number of ILI consultations from ILI surveillance	ILI surveillance in Beijing	Aged 0–4 years: 241 834; Aged 5–14 years: 124 742; Aged 15–24 years: 61 947; Aged 25–59 years: 162 988; Aged 60+ years: 43 943
Ra: age-specific proportion of positive cases from influenza virus surveillance*	Influenza virus surveillance in Beijing	Aged 0–4 years: 10·7%(454/4258); Aged 5–14 years: 20·0%(571/2851); Aged 15–24 years: 16·9%(498/2949); Aged 25–59 years: 20·5%(1652/8069); Aged 60+ years: 23·9%(319/1337)
P: proportion of symptomatic cases among influenza infections	Published study [19]	58·3–74·5%
Q: proportion of ILI cases among symptomatic infections	Published study [16]	26·0–42·0%
Ca: age-specific consultation rates	the fourth National Health Services Survey of China [20]	Aged 0–4 years: 69·2–76·2%; Aged 5–14 years: 57·2–62·2%; Aged 15–24 years: 48·2–52·8%; Aged 25–59 years: 49·6–51·4%; Aged 60+ years: 69·5–72·9%
S: success rate for sampling pharyngeal swab specimens	Published study [16]	80–90%
T: test sensitivity of detection of polymerase chain reaction	Published study [16]	95–100%

ILI, influenza-like illness.

^*Age-specific proportion of positive cases was calculated by dividing the number of positive specimens by the total number of specimens within each age group.