SERIOUS MORBIDITY AND MORTALITY ASSOCIATED WITH INFLUENZA EPIDEMICS

The purpose of this review is to examine current methods of estimation of influenza-related morbidity and mortality from the perspective of surveillance of seven seasons (1974-1981) of influenza virus activity and related disease by the Influenza Research Center in Houston Texas. Virologic surveillance was designed to monitor influenza virus activity in all socioeconomic strata of the population of Harris County Texas which increased from about 2.0 to 2.4 million persons during the study period. The surveillance program has provided some measure of the contribution of influenza virus infections to medically attended acute respiratory illnesses while defining the period of influenza virus prevalence for each season. Nonvirological indexes of epidemic influenza that have been used for regional and national surveillance are evaluated. "Preliminary observations suggest that the number of hospitalizations for acute respiratory illnesses observed in this framework provides a better estimate of impact than data derived from death certificates." (EXCERPT)