Table 4 Summary of estimates in Canada during 2011-2012 and 2012-2013 influenza seasons. Values reported as estimated baseline value and range from variation of recovery rate γ (see section “Sensitivity analysis” for the details of sensitivity analysis)

Seasonal influenza in Canada: 2011-2012 and 2012-2013 influenza seasons

Laboratory-confirmed infections*

10,271

26,671

Estimates generated from modified CDC-defined influenza in RCT

Season

2011-12

2012-13

Percent of influenza cases captured in surveillance

2.6% (2.1−3.2%)

1.2% (0.98−1.2%)

Expansion factor

37.9 (31.0−46.8)

84.8 (69.1−102.6)

Estimated symptomatic influenza illnesses

3.9×10⁵ (3.2×10⁵−4.8×10⁵)

2.3×10⁶ (1.8×10⁶−2.7×10⁶)

Basic reproduction number

1.22 (1.22−1.22)

1.19 (1.19−1.19)

Estimates generated from respiratory illness associated influenza in RCT

Season

2011-12

2012-13

Percent of influenza cases captured in surveillance

0.51% (0.42−0.63%)

0.4% (0.33−0.49%)

Expansion factor

195.1 (159.3−236.1)

252.9 (206.3−306.1)

Estimated symptomatic influenza illnesses

2.0×10⁶ (1.6×10⁶−2.4×10⁶)

6.7×10⁶ (5.5×10⁶−8.2×10⁶)

Basic reproduction number

1.22 (1.22−1.22)

1.19 (1.19−1.19)