Volume 10, Number 1, January 2004

Influenza Epidemics in the United States, France, and Australia, 1972–1997

Cécile Viboud,*† Pierre-Yves Boëlle,*‡ Khashayar Pakdaman,* Fabrice Carrat,*‡ Alain-Jacques Valleron,*‡ Antoine Flahault*†‡
*Institute National de la Santé et de la Recherche Médicale, Paris, France; †World Health Organization Collaborating Center for Electronic Diseases Surveillance, Paris, France; and ‡Hôpitaux de Paris, CHU Saint-Antoine, Paris, France

Figure 4. Synchrony in the timing of the peaks of influenza epidemics for 26 influenza years (1972–1997). Distribution of the time lags between the epidemic peaks in weeks (wk, main plot). The red bars represent the observed lags, and the dashed line represents the distribution of lags obtained by permutations. (inset plot) Distribution of the standard deviation of permuted lags under the assumption of no synchrony. Red arrow indicates the standard deviation in the observed data. A, United States and France, b) United States and Australia, C, France and Australia. Panels B and C illustrate the scenario in which the influenza season in Australia is systematically 6 months before that of the United States or France. Similar results are obtained for the reverse scenario.

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This page last reviewed December 22, 2003

Emerging Infectious Diseases Journal
National Center for Infectious Diseases
Centers for Disease Control and Prevention