The Centers for Disease Control, Atlanta, USA compiled and analyzed data collected from the beginning of the outbreak till 24 July 2009 and this gives a fair idea of the demographic characteristics of H1N1 infl uenza. During this period, 43,771 cases were reported in the USA with the majority being in people under 24 years of age [21] . Few cases were reported in people older than 60 years. The age distribution of the number of cases per 100,000 according to this analysis is given in table 1 [22] .