[Influence of influenza epidemics on the urban population].
The results of studies carried out in 1974-1979 according to the programme of epidemiological survey of influenza among the population of Houston (USA) developed by the Research Center for Influenza at the Baylor Medical College are reviewed. The data of selective virological and epidemiological surveys of the population were used for comparative analysis of several epidemic outbreaks caused by different antigenic variants of influenza virus. The analysis has been aimed at the detection of "high risk" groups of the population, investigation of the effect of influenza on the health of the population, determination of the factors conducive to virus spread, development of methods for the evaluation of the efficacy of influenza control measures, as well as determination of the earliest signs of activity of influenza viruses among the population and search for the best method of prediction of an epidemic virus for the following season.