Fig. 2

Incidence rate of ILI per 1000 person-months in each age group. Vertical bars indicated 95% confidence intervals (CI). No significant difference was observed between those in age group under 2 years and 2–4 years, 71.6 (95%CI 64.7–81.8) and 71.3(65.8–78.2), respectively. The minimum incidence of ILI was 13.0 (11.9–14.1) in 30–44 years