Age Distribution in Seasonal Influenza and Pneumonia Mortality in the United States, 1960-2002

Nobuko Mizoguchi, University of California, Berkeley

This paper analyzes the changing age distribution of seasonal influenza and pneumonia mortality in the United States from 1960-2002 using the Brass relational logit model. The beta parameter in the Brass model was used to examine the age distribution by sex, by seasons, and by pandemic and epidemic years. Results showed that the Brass beta parameter has been gradually increasing over the past few decades, which suggests that flu and pneumonia mortality is shifting to older ages. The Brass alpha parameter was shown to be decreasing, indicating a possible increase in flu and pneumonia mortality. No drop in age distribution for the 1968-69 pandemic season was observed. With the aging of the population, this phenomenon could have significant impact in the event of a future flu pandemic.