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Table 4 Case fatality ratios (mean and 95% CIs) among laboratory-confirmed A/H1N1 influenza cases by pandemic wave, Mexico, 01 April through 31 December, 2009

From: Impact of antiviral treatment and hospital admission delay on risk of death associated with 2009 A/H1N1 pandemic influenza in Mexico

Variable Overall case fatality ratio Pandemic wave P valuea
   Wave 1 Wave 2 Wave 3  
Total A/H1N1 deaths (% of total A/H1N1 cases) 2.1% (2.0,2.3) 4.6% (3.1,6.5) 0.7% (0.5,1.0) 2.5% (2.3,2.7) P < 0.0001
Central 2.7% (2.4,3.0) 5.5% (3.6,8.1) 1.7% (0.8,3.0) 2.7% (2.4,3.0) P < 0.0001
Southern 0.8% (0.6,1.0) 0% (0,6.2) 0.5% (0.3,0.8) 1.2% (0.8,1.7) P < 0.0001
Other states 2.3% (2.1,2.6) 3.2% (0.9,8.1) 0.9% (0.4,1.5) 2.6% (2.2,2.9) P < 0.0001
Demography
Female 2.1% (1.8,2.3) 4.5% (2.5,7.5) 0.6% (0.3,0.9) 2.4% (2.1,2.7) P < 0.0001
Male 2.2% (2.0,2.5) 4.6% (2.5,7.6) 0.9% (0.6,1.3) 2.5% (2.2,2.8) P < 0.0001
Age (years)
<18 0.6% (0.5,0.8) 0.7% (0.1,2.6) 0.1% (0.04,0.3) 0.8% (0.6,0.97) P < 0.0001
18–49 2.8% (2.5,3.1) 6.0% (3.5,9.4) 1.2% (0.8,1.7) 3.2% (2.8,3.6) P < 0.0001
>50 8.5% (7.2,9.8) 15.7% (7.0,28.6) 3.5% (1.6,6.5) 9.1% (7.7,10.6) P < 0.0001
  1. Wave 1 (spring) refers to April 1 through May 20; wave 2 (summer) refers to May 21 through August 1; wave 3 (fall) refers to August 2 through December 31 of 2009.
  2. a Determined by the Chi-square test statistic.