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Table 5 Reproduction numbers from seasonal influenza epidemics

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

Year(s) Type/Subtype Study population Mean GT/SIa Reproduction number (R) 95% CIb Basic or effective Case definition Reference Year published
1889–1890 H3N8? USA & Europe 2.6 2.10 1.9–2.4 Basic Unconfirmed deaths [101] 2010
1948–1949 H1N1 Canada 4.1 1.30   Effective Unconfirmed illness [25] 2006
1949–1950 H1N1 Canada 4.1 1.50   Effective Unconfirmed illness [25] 2006
1950–1951 H1N1 Canada & UK 4.1 2.00 1.9–2.5 Effective Unconfirmed deaths [25] 2006
1958–1973 H2N2; H3N2; B United Kingdom 4.48 3.9–7.1   Effective Unconfirmed illness [102] 1979
1972–2002 H1N1/H3N2/B Australia 5.5 1.30   Effective Unconfirmed deaths [103] 2008
1972–2002 H1N1/H3N2/B France 5.5 1.30   Effective Unconfirmed deaths [103] 2008
1972–2002 H1N1/H3N2/B USA 5.5 1.30   Effective Unconfirmed deaths [103] 2008
1972–2002 H1N1/H3N2/B USA; France; Australia 5.5 1.30 1.2–1.4 Effective Unconfirmed deaths [103] 2008
1975–2004 H1N1/H3N2/B Norway 6 1.06–1.69   Effective Unconfirmed deaths [104] 2010
1976–1981 H1N1/H3N2/B USA 2.6 1.70   Basic Serology confirmed infection [10] 2006
1976–1981 H1N1/H3N2/B USA 4.1 1.16   Basic Serology confirmed infection [105] 2000
1977–1978 H1N1 United Kingdom 2.2 4.38   Basic Unconfirmed illness [106] 2005
1977–1978 H1N1 United Kingdom 3 21.00   Basic Unconfirmed illness [13] 2004
1977–1978 H1N1 United Kingdom 4.70 16.90   Basic Unconfirmed illness [106] 2005
1984–1985 H1N1/H3N2 France 2.49 1.37   Effective Unconfirmed illness [107] 1988
1985–2005 H1N1/H3N2/B United Kingdom 2.2 1.6–2.1   Basic Unconfirmed illness [108] 2010
1985–2005 H1N1/H3N2/B United Kingdom 2.7 1.6–2.5   Basic Unconfirmed illness [109] 2012
1985–2006 H1N1/H3N2/B France 2.4 1.4–1.7 1.3–1.8 Basic Unconfirmed illness [110] 2008
1996–2006 H1N1/H3N2/B Brazil 3 1.03 1.02–1.04 Effective Unconfirmed deaths [111] 2010
1998–1999 H3N2 Israel 3 1.14   Effective Unconfirmed illness [112] 2011
1998–1999 H3N2 Israel 3 1.16   Effective Unconfirmed illness [112] 2011
1998–1999 H3N2 USA 3 1.18 1.05–1.25 Effective Laboratory confirmed illness [113] 2009
1998–2009 H1N1/H3N2/B Israel 2.5 1.17–1.62   Effective Unconfirmed illness [114] 2012
1999–2000 H3N2 Israel 3 1.16   Effective Unconfirmed illness [112] 2011
1999–2000 H3N2 Israel 3 1.18   Effective Unconfirmed illness [112] 2011
1999–2006 Seasonal H1N1 Taiwan 2 1.19 0.76–1.86 Basic Confirmed and unconfirmed illness [115] 2010
1999–2006 H3N2 Taiwan 3 1.41 0.92–2.19 Basic Confirmed and unconfirmed illness [115] 2010
1999–2006 B Taiwan 3 1.07 0.69–1.69 Basic Confirmed and unconfirmed illness [115] 2010
2000–2001 H1N1 Israel 3 1.12   Effective Unconfirmed illness [112] 2011
2000–2009 H1N1/H3N2/B Italy 4 1.17–1.36   Effective Unconfirmed illness [116] 2012
2001–2002 H3N2 Israel 3 1.25   Effective Unconfirmed illness [112] 2011
2001–2002 H3N2 Israel 3 1.27   Effective Unconfirmed illness [112] 2011
2003–2004 H3N2 Israel 3 1.19   Effective Unconfirmed illness [112] 2011
2003–2004 H3N2 Israel 3 1.21   Effective Unconfirmed illness [112] 2011
2003–2004 H3N2 Switzerland 2.6 1.2–1.3   Effective Unconfirmed illness [117] 2011
2004–2005 H3N2 Israel 3 1.25   Effective Unconfirmed illness [112] 2011
2004–2005 H3N2 Israel 3 1.25   Effective Unconfirmed illness [112] 2011
2004–2005 unspecified Taiwan 4.1 1.00   Effective Unconfirmed deaths [118] 2010
2004–2005 H3N2 USA 7 1.20 1.1–1.3 Effective Laboratory confirmed illness [119] 2008
2006–2007 H3N2 Israel 3 1.28   Effective Unconfirmed illness [112] 2011
2006–2007 H3N2 Israel 3 1.33   Effective Unconfirmed illness [112] 2011
2007–2008 H3N2 Israel 3 1.25   Effective Unconfirmed illness [112] 2011
2007–2008 H3N2 Israel 3 1.29   Effective Unconfirmed illness [112] 2011
2011/12 H1N1 Mexico 3 1.20   Effective Laboratory confirmed hospitalizations [120] 2012
2011/12 H1N1 Mexico 3 1.20   Effective Laboratory confirmed hospitalizations [121] 2012
2011/12 H1N1 Mexico 4 1.30   Effective Laboratory confirmed hospitalizations [121] 2012
Median reproduction number for seasonal influenza: 1.28; Interquartile range 1.19–1.37
  1. aThe generation time (GT) or serial interval (SI) assumed in the reproduction number estimation
  2. bConfidence interval
  3. NR = Not reported
  4. This table is also available as a .csv file as Additional file 5.