1. Presentation Topic : Vaccination Deployment in Protection against Influenza A (H1N1) Infection PhD Student : Shang XIA Supervisor : Prof. Jiming LIU Department of Computer Science March 15, 2010 11th Postgraduate Research Symposium Co-supervisor : Dr. William Kwok-Wai

2. Content: 1 2 Research Motivation & Objectives Epidemic Infection Dynamics 3 Vaccine Deployment Factors 4 SIV model and Vaccination Simulation Page 1/17 5 Conclusion

3.  Vaccination Dynamics  Disease Diffusion Dynamics Global Dynamics  Social Contact Network  Entities Infection Model  Decision Making Local Behaviors Global Epidemic Spreading Dynamics Previous Work : Page 2/17

4.  Epidemic Spreading  Epidemic Interventions Background : Virus Infection : Individuals’ pathological infection. Virus Transmission : Individuals’ contact relationship. Vaccine Immunization : Individual immunized from virus infection. Contact Limitations : Population’s contact landscape reconstructed. Page 3/17

5.  Simulation Model of Infection Dynamics  Evaluation of Vaccination Deployment Research Concerns : Pathological Infection : Heterogeneity of individual’s infection vulnerability. Contact Transmission : Heterogeneity of Individuals’ contact frequency. Vaccine Availability :  Total amount of vaccine doses.  Starting time of vaccine releasing. Vaccine Distribution : Vaccination priority of each population group. Page 4/17

6.  Model of Simulating Virus Infection Dynamics Virus Infection Model : Infection Status Label  Three status labels: Susceptible (S), Infected (I), Vaccinated (V). Host Population Structure :  Population are divided into 6 Age Groups. Heterogeneity of Vulnerability  Differentiation of Infection Rate and Recovery Rate for individual in each age group. Heterogeneity of Transmissibility : Contact Frequency within and cross each Age Groups. S-I-V Model Page 5/17

7. Virus Infection Model (Con.) (Ref. 1) (Ref. 2) (Ref.3) Page 6/17

8.  Factors in Vaccination Deployment Plan Vaccination Deployment : Vaccine Availability  Total Amount of Vaccine The proportion of vaccinated population of the host.  Releasing Time The time of first batch of vaccine being released. Vaccine Distribution  Vaccination Priority for each age groups.  Vaccination by Vulnerability.  Vaccination by Transmissibility. Page 7/17

9. Vaccination Deployment (Con.) 1. The amount of total vaccine doses: Low Quantity5 million8% Middle Quantity10 million16% Ample Quantity20 million32% 2. Vaccine Releasing Time: Pre-epidemic spreadingT = 0 day Incipient Infection StageT = 50 day Infection Mass Spreading StageT = 100 day Infection Stable StageT = 150 day  Settings of Vaccination Deployment 3. Vaccine Distribution Priority Vaccination by VulnerabilityGroup 1(0-4) & Group 6 (65+) Vaccination by TransmissibilityGroup 3 (15-24) & Group 4(25-44) Vaccination by RandomAll 6 Groups Page 8/17

10. Simulation of Infection Dynamics  Three Stages of Infection Dynamics without Vaccination Page 9/17

11. Simulation of Infection Dynamics Incipient Infection Stage  The total percentage of infections is relatively low.  The speed of newly increased infection is slow.  Infection Transmission is confined within initial groups. Infection Mass Spreading Stage  The number of newly increased infection are increased sharply.  The infection positive feedback through cross group contact. Infection Stable Stage  The total number of infection is high.  The increase of newly infection is stagnant.  The cross group infection keep at a high level. Page 10/17

12. Simulation of Vaccination Deployment  The impact of the Amount of Vaccine Page 11/17

13. Simulation of Vaccination Deployment  The impact of the Vaccine Releasing Page 12/17

14. Simulation of Vaccination Deployment  The impact of the Vaccine Distribution Page 13/17

15. Simulation of Vaccination Deployment  The Impact of three Vaccine Deployment Factors Total AmountReleasing TimeVaccine Distribution Increase vaccine amount Earlier Releasing TimeRandomlyTransmissibilityVulnerability Risk of Infectious Contact Lowered Lowered: T>R>V Risk of Successful Infection Lowered: V>R>T Tipping Point of Phase Transition Delayed Infection Rising Time Prolonged Prolonged: V>T>R Speed of Convergence to Stable Infection Slowed Slowed: V>T>R Stable Infection Percentage Decreased Decreased: V>T>R Page 14/17

16.  SIV Model  Evaluation of Vaccination Deployment Factors Conclusion : Pathological Infection : Heterogeneity of individual’s infection vulnerability. Contact Transmission : Heterogeneity of Individuals’ contact frequency. Vaccine Availability :  Total amount of vaccine doses.  Starting time of vaccine releasing. Vaccine Distribution : Vaccination priority of each population group. Page 15/17

17. 1.C. Wroth and A. Wiles. Key population and vital statistics. Technical report, Office for National Statistics, 2007. 2.J. Mossong, ect. Social contacts and mixing patterns relevant to the spread of infectious diseases. PLoS Medicine, 5(3), March 2008. 3.E. Miller, K. Hoschler, ect. Incidence of 2009 pandemic influenza a h1n1 infection in england: a cross-sectional serological study. The Lancet, Early Online Publication. Reference : Page 16/17

18. Q & A Thank You Very Much!