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Activity Number:
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146
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Type:
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Contributed
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Date/Time:
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Monday, August 7, 2006 : 10:30 AM to 12:20 PM
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Sponsor:
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Section on Statistics in Epidemiology
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| Abstract - #305644 |
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Title:
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A Mathematical Model for the Influence of the Pneumococcal Vaccine on S. pneumoniae Vaccine and Nonvaccine Serotypes
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Author(s):
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Robertino Mera*+
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Companies:
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GlaxoSmithKline
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Address:
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5 Moore Drive, Research Triangle Park, NC, 27709,
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Keywords:
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Streptococcus pneumoniae ; mathematical models ; mixed effect models
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Abstract:
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Coverage of a conjugate vaccine that provides protection against the most common serotypes was 73% in 2004. Concern exists over an increase in carriage and disease by nonvaccine serotypes. A deterministic transmission model was used to study how vaccination and herd immunity (direct and indirect effects) influence the coexistence of vaccine and nonvaccine serotypes. Insights from the mathematical model were utilized to fit a generalized linear mixed-effects model to surveillance data from before (1998--1999) and after (2003--2004) the introduction of the vaccine. Direct and indirect effects act solely through the transmission coefficient on the reproductive number equation. The model correctly predicts complete serotype switch before coverage reaches 90% due to population herd immunity. Serotype replacement was complete by 2004, with a lower prevalence of invasive disease.
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