Since the H1N1 pandemic in 2009, numerous field investigations and epidemiological studies have investigated the spatial-temporal dynamics, geographic distribution and patient characteristics of the 2009 H1N1 pandemic. Through analyses of a total of 377 H1N1associated deaths in the United States, Fowlkes et al. demonstrated that the H1N1-associated mortality rate varied substantially in different geographic regions (i.e. highest in Hawaii, New York and Utah) and in different age groups of the infected population (i.e. 76% in patients aged 18-65 years and 9% in patients aged $ 65 years) [5] . Similar geographic region-and patient age-dependent incidence of H1N1 infection and subsequent mortality have also been demonstrated in South America [6] , and Australia [7] . In addition, the susceptibility to H1N1 infection may vary in different races; Wenger et al. shown that Alaska Native people and Asian/ Pacific Islanders (A/PI) were 2-4 times more likely to be infected by H1N1 virus and hospitalized than white Caucasians [8] .