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Table 4 Reproduction numbers from the 2009 influenza A/H1N1 pandemic

From: Estimates of the reproduction number for seasonal, pandemic, and zoonotic influenza: a systematic review of the literature

Location Wavea Study population Mean GT/SIb Reproduction number (R) 95% CIc Basic or effective Case definition Reference Year published
Mexico 0 Community 1.91 1.25 0.76–1.74 Basic Laboratory confirmed illness [44] 2011
Australia 1st Community 2.8 1.50 1.50–2.70 Effective Laboratory confirmed illness [45] 2010
Australia 1st Community 2.8 1.20 1.0–1.4 Effective Laboratory confirmed illness [45] 2010
Australia 1st Community 2.9 2.40 2.3–2.4 Effective Laboratory confirmed illness [46] 2009
Australia, rural 1st Community 2.9 1.28 1.26–1.30 Effective Laboratory confirmed illness [47] 2011
Australia, urban 1st Community 2.9 1.26 1.22–1.30 Effective Laboratory confirmed illness [47] 2011
Canada 1st Community 1.91 1.30 1.12–1.47 Basic Laboratory confirmed illness [48] 2010
Canada 1st Community 2.78 2.21 1.98–2.50 Basic Laboratory confirmed illness [49] 2012
Canada 1st Community 3.6 1.63 1.31–1.96 Basic Laboratory confirmed illness [48] 2010
Canada 1st Community 4.31 1.31 1.25–1.38 Basic Laboratory confirmed illness [50] 2010
Chile 1st Community 2.5 1.80 1.6–2.0 Effective Unconfirmed emergency room visits [51] 2010
Chile, central 1st Community 3 1.32 1.27–1.37 Effective Unconfirmed hospitalizations [52] 2012
Chile, northern 1st Community 3 1.19 1.13–1.24 Effective Unconfirmed hospitalizations [52] 2012
Chile, southern 1st Community 3 1.58 1.45–1.72 Effective Unconfirmed hospitalizations [52] 2012
China 1st Community 2.6 1.25 1.22–1.28 Effective Laboratory confirmed illness [53] 2012
China 1st Community 4.31 1.53 1.45–1.60 Basic Laboratory confirmed illness [54] 2012
China 1st Community NR 1.68   Basic Laboratory confirmed illness [55] 2011
Hong Kong 1st Community 3 1.70 1.6–1.8 Effective Laboratory confirmed illness [56] 2010
Hong Kong 1st Community 3.2 1.45 1.4–1.5 Effective Laboratory confirmed illness [57] 2010
Israel 1st Community 2.92 1.06 0.97–1.16 Effective Laboratory confirmed illness [58] 2011
Italy 1st Community 2.6 1.30 1.23–1.32 Effective Unconfirmed illness [59] 2012
Japan 1st School 1.9 2.30 2.0–2.6 Effective Laboratory confirmed illness [60] 2009
Japan 1st Community 2.7 1.28 1.23–1.33 Effective Laboratory confirmed illness [60] 2009
Mexico 1st Community 1.91 1.58 1.34–2.04 Basic Unconfirmed illness [61] 2009
Mexico 1st Community 1.96 1.42   Basic Unconfirmed illness [62] 2010
Mexico 1st Community 2.6 1.40 1.2–1.9 Basic Laboratory confirmed illness [61] 2009
Mexico 1st Community 2.6 1.22 1.05–1.60 Basic Laboratory confirmed illness [61] 2009
Mexico 1st Community 3 1.80 1.78–1.81 Effective Unconfirmed illness [63] 2011
Mexico 1st Community 3 1.43 1.29–1.57 Effective Laboratory confirmed illness [64] 2009
Mexico 1st Community 3.1 2.20 2.1–2.4 Effective Laboratory confirmed illness [65] 2009
Mexico 1st Community 3.5 2.30 2.1–2.5 Basic Laboratory confirmed illness [11] 2009
Mexico 1st Community 3.6 1.75 1.6–1.9 Basic Seeding from Mexico [66] 2009
Mexico 1st Community 4.1 3.10 2.9–3.5 Effective Laboratory confirmed illness [65] 2009
Mexico City 1st Community 3 1.72   Basic Laboratory confirmed illness [67] 2009
Morocco 1st Community 2.3 1.44 1.32–1.56 Basic Laboratory confirmed illness [68] 2012
Morocco 1st Community 2.7 1.40 1.34–1.48 Basic Laboratory confirmed illness [68] 2012
Netherlands 1st Community 3 0.50   Effective Laboratory confirmed illness [69] 2009
New Zealand 1st Community 2.7 1.25 1.07–1.47 Effective Laboratory confirmed illness [70] 2011
New Zealand 1st Community 2.8 1.96 1.80–2.15 Effective Laboratory confirmed illness [71] 2009
New Zealand 1st Community 2.8 1.55 1.16–1.86 Effective Laboratory confirmed illness; unconfirmed illness [72] 2010
North America 1st Community 2.7 1.3–2.1   Basic Laboratory confirmed illness [73] 2010
Peru 1st Community 2.8 1.37 1.33–1.41 Effective Laboratory confirmed illness [74] 2009
Peru 1st Community 3 1.30 1.3–1.3 Effective Unconfirmed illness [75] 2011
Peru, Lima 1st Community 3 1.70 1.6–1.7 Effective Unconfirmed illness [75] 2011
Singapore 1st Dance club 1.91 1.9–2.1   Basic Laboratory confirmed illness [76] 2010
Singapore 1st Military NR 1.91 1.50–2.36 Effective Laboratory confirmed and unconfirmed illness [77] 2010
South Africa 1st Community 2.3 1.43 1.38–1.49 Effective Laboratory confirmed illness [78] 2012
South Africa 1st Community 2.78 1.47 1.30–1.72 Effective Laboratory confirmed illness [78] 2012
South Africa 1st Community 2.78 1.42 1.20–1.71 Effective Laboratory confirmed illness [78] 2012
Southern Hemisphere 1st Community 1.9 1.16–1.53   Effective Laboratory confirmed illness [79] 2010
Southern Hemisphere 1st Community 2.60 1.33 1.28–1.45 Basic Laboratory confirmed and unconfirmed illness [80] 2011
Taiwan 1st Community 1.91 1.14 1.04–1.25 Effective Laboratory confirmed illness [81] 2011
Taiwan 1st Community NR 1.16 0.98–1.34 Effective Serology confirmed infection [82] 2011
Thailand 1st Community 1.9 1.78 1.67–1.89 Basic Laboratory confirmed illness [83] 2009
Thailand 1st Community 2.6 2.07 1.92–2.22 Basic Laboratory confirmed illness [83] 2009
United Kingdom 1st School 2.2 1.33 1.11–1.56 Effective Laboratory confirmed illness [84] 2012
United Kingdom 1st Community 2.5 1.44 1.27–1.63 Effective Laboratory confirmed illness [85] 2009
USA 1st Community 2.2 1.70 1.4–2.1 Basic Laboratory confirmed illness [86] 2009
USA 1st Community 2.6 2.20 1.4–2.5 Basic Laboratory confirmed illness [86] 2009
USA 1st School 2.7 3.30 3.0–3.6 Effective Unconfirmed illness [87] 2009
USA 1st Community 3.5 1.3–2.0 1.0–2.2 Basic Laboratory confirmed illness [11] 2009
USA 1st Camp attendees 7 2.20 1.4–3.3 Effective Unconfirmed illness [88] 2011
Vietnam 1st Community 1.9 1.50 1.5–1.6 Basic Laboratory confirmed illness [89] 2010
Vietnam 1st Community 3.6 2.00 1.9–2.2 Basic Laboratory confirmed illness [89] 2010
worldwide 1st Community 2.67 1–2   Effective Laboratory confirmed illness [90] 2011
China 2nd Community 4 1.66 1.27–2.05 Effective confirmed hospitalizations [91] 2012
China 2nd Community 4.3 1.70 1.4–1.9 Effective Laboratory confirmed illness [92] 2010
France 2nd Military 2.9 1.5–1.6   Effective Unconfirmed illness [93] 2012
Iran 2nd school NR 1.28 1.05–1.54 Basic Unconfirmed illness [94] 2012
Italy 2nd Community 2.5 1.33   Effective Unconfirmed illness [95] 2011
Japan 2nd Community 3 1.48 1.41–1.56 Effective Unconfirmed illness [96] 2012
Mexico 2nd Community 3 1.62 1.61–1.63 Effective Unconfirmed illness [63] 2011
Reunion Island 2nd Community 2.8 1.26 1.08–1.49 Effective Unconfirmed illness [97] 2010
Taiwan 2nd Community 1.91 1.02 1.01–1.02 Effective Laboratory confirmed illness [81] 2011
Taiwan 2nd Community NR 1.87 1.68–2.06 Effective Serology confirmed infection [82] 2011
United Kingdom 2nd Community 2.5 1.30 1.2–1.5 Effective Laboratory confirmed illness [98] 2010
Mexico 3rd Community 3 1.24 1.23–1.24 Effective Unconfirmed illness [63] 2011
various   Community NR 1.30 1.1–1.4 Effective Serology confirmed infection [99] 2012
Median reproduction number for the 2009 pandemic: 1.46; Interquartile range 1.30–1.70
  1. aThe 2009 influenza A/H1N1 pandemic began in Mexico in the late winter or early spring of 2009 [44]. The United States and the United Kingdom experienced a first wave of illnesses in the Spring of 2009 followed by a second wave during the Fall of 2009 [4]. However, unlike these three countries, a number of countries, especially in the Southern Hemisphere, only experienced a single wave of illnesses [100].
  2. bThe generation time (GT) or serial interval (SI) assumed in the reproduction number estimation.
  3. cConfidence interval.
  4. NR = Not reported.
  5. This table is also available as a .csv file as Additional file 4.