Objective To explore the trend of influenza epidemics,predominate strains of the virus in Tianjin city and to analyze the economic impact of vaccine-based interventions for the prevention and control of influenza. Methods Data on epidemiological studies and on virus surveillance was gathered. Monte Carlo mathematical simulation modelwas used for data analyses. Results From 29 ,December,2003 to 2, January, 2005, the proportion of influenza-like infection cases was accounted for 8.93% of the total number of p...