Influenza and pneumonia hospitalizations in Ontario: a time-series analysis.

A comprehensive examination of gender and age-specific influenza and pneumonia hospitalization seasonality is currently lacking. Using population-based data for Ontario, Canada between April 1988 and March 2002 (n = 339,803 hospitalizations), findings from this study revealed clear seasonality [Fisher's Kappa (FK) test = 68.64, P < 0.001; Bartlett's Kolmogorov-Smirnov (BKS) test = 0.68, P < 0.001] with consistent summer troughs and winter peaks for both sexes and all ages combined. The very young (both sexes 0-4 years) demonstrated the strongest seasonality (R2(autoreg) = 0.97) and females aged 10-19 years, the weakest (R2(autoreg) = 0.59). Gender differences were most pronounced in the oldest age groups (80+ years) where females had an average annualized peak rate of 250/100,000 compared to 400/100,000 for males. These findings can contribute to more population-specific prevention strategies and effective resource and service allocation based on seasonal and specific population demands.