The Global Implications of Influenza in Hong Kong

Abstract
Was the disappearance of brooding storks in Germany during the latter half of the last century really responsible for the precipitous decline in the number of newborn babies there? This example illustrates why ecologic studies are considered among the weakest of epidemiologic methods. Nonetheless, in 1847, this relatively crude descriptive approach was sufficient to allow William Farr to show a strong correlation between the incidence of influenza-like illness and the annual excess of deaths in winter. Since then, public health practitioners have used variations on the ecologic approach to quantify the annual burden of influenza (Figure 1). After influenza A . . .