Scaling in the Global Spreading Patterns of Pandemic Influenza A and the Role of Control: Empirical Statistics and Modeling
(Submitted on 8 Dec 2009)
The pandemic of influenza A (H1N1) is a serious on-going global public crisis. Understanding its spreading dynamics is of fundamental importance for both public health and scientific researches. In this paper, we investigate the spreading patterns of influenza A and find the Zipf's law of the distributions of confirmed cases in different levels. Similar scaling properties are also observed for severe acute respiratory syndrome (SARS) and bird cases of avian influenza (H5N1). To explore the underlying mechanism, a model considering the control effects on both the local growth and transregional transmission is proposed, which shows that the strong control effects are responsible for the scaling properties. Although strict control measures for interregional travelers are helpful to delay the outbreak in the regions without local cases, our analysis suggests that the focus should be turned to local prevention after the outbreak of local cases. This work provides not only a deeper understanding of the generic mechanisms underlying the spread of infectious diseases, but also an indispensable tool to decision makers to adopt suitable control strategies.