Understanding Trends in Pertussis Incidence: An Agent-Based Model Approach
Authored by Erinn Sanstead, Cynthia Kenyon, Seth Rowley, Eva Enns, Claudia Miller, Kristen Ehresmann, Shalini Kulasingam
Date Published: 2015
DOI: 10.2105/ajph.2015.302794
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Abstract
Objectives. We examined the impact of undetected infections, adult
immunity, and waning vaccine-acquired immunity on recent age-related
trends in pertussis incidence.
Methods. We developed an agent-based model of pertussis transmission in
Dakota County, Minnesota using case data from the Minnesota Department
of Health. For outbreaks in 2004, 2008, and 2012, we fit our model to
incidence in 3 children's age groups relative to adult incidence. We
estimated parameters through model calibration.
Results. The duration of vaccine-acquired immunity after completion of
the 5-dose vaccination series decreased from 6.6 years in the 2004 model
to approximately 3.0 years in the 2008 and 2012 models. Tdap waned after
2.1 years in the 2012 model. A greater percentage of adults were immune
in the 2008 model than in the 2004 and 2012 models. On average, only 1
in 10 adult infections was detected, whereas 8 in 10 child infections
were detected.
Conclusions. The observed trends in relative pertussis incidence in
Dakota County can be attributed in part to fluctuations in adult
immunity and waning vaccine-acquired immunity. No single factor accounts
for current pertussis trends.
Tags
Infection
transmission
Children
Adults
Changing epidemiology
Waning immunity
Vaccine
Tetanus