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Table 1 Reproduction numbers from the 1918 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
Australia 1st Community 2.6 1.80 1.6–2.0 Basic Unconfirmed hospitalizations/deaths [15] 2008
Brazil 1st Community 4 2.68   Basic Unconfirmed illness [16] 2007
Canada 1st Community 3 1.50 1.5–1.5 Basic Unconfirmed deaths [17] 2011
Canada 1st Community 6 2.1 2.1–2.1 Basic Unconfirmed deaths [17] 2011
Colombia 1st Community 3 1.4–1.5   Effective Unconfirmed deaths [18] 2012
Colombia 1st Community 4 1.5–1.7   Effective Unconfirmed deaths [18] 2012
Denmark 1st Community 2.6 2.2–2.4   Effective Unconfirmed illness [19] 2008
Denmark 1st Community 4 2.8–3.0   Effective Unconfirmed illness [19] 2008
Denmark 1st Community 2.6 2.8–4.0   Effective Unconfirmed hospitalizations [19] 2008
Denmark 1st Community 4 3.6–5.4   Effective Unconfirmed hospitalizations [19] 2008
Italy 1st Community 3 1.03 1.00–1.08 Basic Unconfirmed hospitalizations [20] 2011
Mexico 1st Community 3 1.30   Effective Unconfirmed deaths [21] 2010
Peru 1st Community 3 1.38 1.37–1.40 Effective Unconfirmed deaths [22] 2011
Switzerland 1st Community 3.11 1.49 1.45–1.53 Basic Unconfirmed hospitalizations [23] 2006
Switzerland 1st Community 3.4 1.50   Basic Unconfirmed deaths [24] 2009
United Kingdom 1st Community 2.6 1.7   Basic Unconfirmed deaths [10] 2006
United Kingdom 1st Community 4.1 2.10   Effective Unconfirmed illness [25] 2006
United Kingdom 1st Community 6 2.00   Basic Unconfirmed illness [26] 2005
United Kingdom 1st Community NR 1.16–2.94   Effective Unconfirmed illness [27] 2010
United Kingdom 1st Students NR 1.43–5.36   Effective Unconfirmed illness [27] 2010
USA 1st Community 4 1.34–3.21   Effective Unconfirmed illness [28] 2008
Various 1st Community 4 1.2–3.0   Effective Unconfirmed illness [29] 2007
Various 1st Community 4 2.1–7.5   Effective Unconfirmed illness [29] 2007
  1st Sailors 4 4.97   Effective Unconfirmed illness [28] 2008
Canada 2nd Community 3.6 2.26 1.95–2.63 Basic Unconfirmed illness [30] 2010
Canada 2nd Community 3.6 1.49 1.42–1.55 Basic Unconfirmed illness [30] 2010
Canada 2nd Community 3 2.40 2.4–2.5 Basic Unconfirmed deaths [17] 2011
Canada 2nd Community 6 4.3 4.2–4.4 Basic Unconfirmed deaths [17] 2011
Denmark 2nd Community 2.6 1.22–1.24   Effective Unconfirmed illness [19] 2008
Denmark 2nd Community 4 1.29–1.33   Effective Unconfirmed illness [19] 2008
Denmark 2nd Community 2.6 1.2–1.3   Effective Unconfirmed hospitalizations [19] 2008
Denmark 2nd Community 4 1.3–1.4   Effective Unconfirmed hospitalizations [19] 2008
Germany 2nd Community 1 1.58 0.03–10.3 Basic Unconfirmed deaths [31] 2007
Germany 2nd Community 3 2.52 0.75–5.85 Basic Unconfirmed deaths [31] 2007
Germany 2nd Community 5 3.41 1.91–5.57 Basic Unconfirmed deaths [31] 2007
Italy 2nd Community 3 1.38 1.3–1.5 Basic Unconfirmed hospitalizations [20] 2011
Mexico 2nd Community 3 1.30   Effective Unconfirmed deaths [21] 2010
New Zealand 2nd Military >1.5 1.3–3.1   Basic Unconfirmed hospitalizations [32] 2006
Switzerland 2nd Community 2.28 3.75 3.6–3.9 Effective Unconfirmed hospitalizations [23] 2006
Switzerland 2nd Community 3.4 2.40   Basic Unconfirmed deaths [24] 2009
United Kingdom 2nd Community 3 1.39 1.36–1.43 Effective Unconfirmed deaths [33] 2008
United Kingdom 2nd Community 6 1.84 1.75–1.92 Effective Unconfirmed deaths [33] 2008
United Kingdom 2nd Community 6 1.55   Basic Unconfirmed illness [26] 2005
United Kingdom 2nd Community 2.6 1.50   Basic Unconfirmed deaths [10] 2006
USA 2nd Community 2.5 2.14   Basic Unconfirmed deaths [34] 2009
USA 2nd Community NR 2.20 1.55–2.84 Effective Unconfirmed illness [35] 2007
USA 2nd Community 4 2.00 1.7–2.3 Effective Unconfirmed deaths [36] 2004
USA 2nd Community 2.85 1.73   Effective Unconfirmed deaths [14] 2007
United Kingdom 3rd Community 3 1.39 1.29–1.49 Effective Unconfirmed deaths [33] 2008
United Kingdom 3rd Community 6 1.82 1.61–2.05 Effective Unconfirmed deaths [33] 2008
United Kingdom 3rd Community 6 1.70   Basic Unconfirmed illness [26] 2005
Median reproduction number for the 1918 pandemic: 1.80; Interquartile range 1.47–2.27
  1. aThe first wave of illnesses began in the Northern Hemisphere in the spring 1918 [1]. A second wave of more intense transmission occurred concurrently in North America, Europe, and Africa in the Fall of 1918 while a third and final wave of activity occurred in some areas of the world during the winter of 1919 [37].
  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 1.
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