报告题目：Host Contact Structure is Important for the Recurrence of Influenza A(人群接触结构是甲型流感反复流行的重要因素)
报告人：马君岭,加拿大维多利亚大学（University of Victoria ）数学与统计系助理教授。1994年于西安交通大学应用数学专业本科毕业，1997年获西安交通大学应用数学硕士，2003年获普林斯顿大学（Princeton University）应用数学博士学位，主要从事传染病建模与控制研究。
报告摘要：An important characteristic of influenza A is its ability to escape host immunity through antigenic drift. A novel influenza A strain that causes a pandemic confers full immunity to infected individuals, yet because of antigenic drift, these individuals have decreased immunity to drifted strains. We compute the required decrease in immunity so that a recurrence is possible. Models for influenza A must make assumptions on the contact structure on which the disease spreads. By determining the local stability of the disease free equilibrium via the reproduction number, we show that the classical random mixing assumption predicts an unrealistically large decrease of immunity before a recurrence is possible. We improve over the classical random mixing assumption by incorporating a contact network structure. A complication of contact networks is correlations induced by the initial pandemic. Thus in this presentation, we provide a novel analytic derivation of such correlations and show that contact networks may require a dramatically smaller drop in immunity before recurrence. Hence, the key new insight in our work is that on contact networks the establishment of a new strain is possible for much higher immunity levels of previously infected individuals than predicted by the commonly used random mixing assumption. This suggests that stable contacts like classmates, coworkers and family members are a crucial path for the spread of influenza in human population.