Age-Dependent Estimates of the Epidemiological Impact of Pandemic Influenza (H1N1-2009) in Japan
Figure 3
Estimated proportions of influenza infections and cases from 2009 to 2010. (a) The estimated proportion infected by age group. Ignoring short-term decay in antibody titer, the proportion infected during the first wave of the 2009 pandemic was calculated as the difference between the proportions above a cut-off level of titer in 2009 and 2010. In both years, the survey took place from July to September. We adopted 1 : 20 (unfilled circles) and 1 : 40 (filled diamonds) as the cut-off values. Whiskers extend from lower to upper 95% confidence intervals. (b) The estimated proportion of influenza-like illness (ILI) cases with medical attendance by age group. The notified number of cases from week 28 in 2009 to week 10 in 2010 was used to estimate the total number of ILI cases with medical attendance, using the proportion of sentinel medical institutions among the total number of medical institutions across Japan.
