Presentation Topic :Presentation Topic :

Vaccination Deployment in Protection Vaccination Deployment in Protection against Influenza A (H1N1) Infectionagainst Influenza A (H1N1) Infection

PhD Student : Shang XIASupervisor : Prof. Jiming LIU

Department of Computer Department of Computer ScienceScience

March 15, 2010 March 15, 2010

11th Postgraduate Research Symposium

Co-supervisor : Dr. William Kwok-Wai

ContenContent:t:

1

2

Research Motivation & Objectives

Epidemic Infection Dynamics

3 Vaccine Deployment Factors

4 SIV model and Vaccination Simulation

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5 Conclusion

Individual State Change

Global Epidemic Spreading Dynamics

Disease Diffusion Dynamics Local-Global

Relationship

Local Interaction

Individual Decision Making

History Records

Environment Evaluation

Individual Decision Making

History Records

Environment Evaluation

Social Contact Network

Individual State Transition

Individual Vaccination Choice

Disease Infection

Population Immunization Patterns

Individual Vaccination Decision

Epidemic Spreading Dynamics

Individual State Transition

Vaccination Dynamics

Disease Diffusion Dynamics

Global Dynamics

Social Contact Network

Entities Infection Model

Decision Making

Local Behaviors

Global Epidemic Spreading Dynamics

Previous Previous WorkWork::

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Epidemic Spreading

Epidemic Interventions

BackgrouBackgroundnd::

Virus Infection: Individuals’ pathological

infection. Virus Transmission:

Individuals’ contact relationship.

Vaccine Immunization: Individual immunized from virus

infection. Contact Limitations:

Population’s contact landscape reconstructed.

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Simulation Model of Infection Dynamics

Evaluation of Vaccination Deployment

Research Research ConcernsConcerns::

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.

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Model of Simulating Virus Infection Dynamics

Virus Infection Virus Infection ModelModel::

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 S-I-V ModelModel

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Virus Infection Model Virus Infection Model (Con.)(Con.)I

V

S

Group 1(0-4)

I

V

S

Group 2(5-14)

I

V

S

Group 3(15-24)

I

V

S

Group 4(25-44)

I

V

S

Group 5(45-64)

I

V

S

Group 6(65+)

Contact Activities

Contact Activities

Contact Activities

(Ref. 1)

(Ref. 2)

(Ref.3)

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Factors in Vaccination Deployment Plan

Vaccination Vaccination DeploymentDeployment::

Vaccine Availability Total Amount of Vaccine

The proportion of vaccinated population of the host.

Releasing TimeThe time of first batch of vaccine being

released.

Vaccine Distribution Vaccination Priority for each age groups.

Vaccination by Vulnerability. Vaccination by Transmissibility.

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Vaccination DeploymentVaccination Deployment (Con.)(Con.)

1. The amount of total vaccine doses:

Low Quantity 5 million 8%

Middle Quantity 10 million 16%

Ample Quantity 20 million 32%

2. Vaccine Releasing Time:Pre-epidemic spreading T = 0 day

Incipient Infection StageT = 50

day

Infection Mass Spreading Stage

T = 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 Transmissibility

Group 3 (15-24) & Group 4(25-44)

Vaccination by Random All 6 Groups

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Simulation of Infection Simulation of Infection DynamicsDynamics

Virus Infection Dynamics without Vaccination

S1 S2 S3

S1: Incipient Infection StageS2: Mass Spreading Infection StageS3: Stable Infection Stage

Three Stages of Infection Dynamics without Vaccination

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Simulation of Infection Simulation of Infection DynamicsDynamics 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.

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Simulation of Vaccination Simulation of Vaccination DeploymentDeployment The impact of the Amount of Vaccine

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Simulation of Vaccination Simulation of Vaccination DeploymentDeployment The impact of the Vaccine Releasing

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Simulation of Vaccination Simulation of Vaccination DeploymentDeployment The impact of the Vaccine Distribution

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Simulation of Vaccination Simulation of Vaccination DeploymentDeployment The Impact of three Vaccine Deployment

Factors

Total AmountReleasing

Time Vaccine Distribution

Increase vaccine amount

Earlier Releasing

TimeRandom

lyTransmissibil

ity Vulnerabilit

y

Risk of Infectious Contact Lowered   Lowered: T>R>VRisk of Successful Infection     Lowered: V>R>TTipping Point of Phase Transition Delayed Delayed  Infection Rising Time Prolonged Prolonged Prolonged: V>T>RSpeed of Convergence to Stable Infection Slowed Slowed Slowed: V>T>RStable Infection Percentage Decreased   Decreased: V>T>R

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SIV Model

Evaluation of Vaccination Deployment Factors

ConclusionConclusion::

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.

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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.

ReferenceReference::

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Q & AQ & A

Thank You Very Much!