COS 104-9 - Estimating the duration of pertussis immunity using epidemiological signatures

Thursday, August 6, 2009: 4:20 PM
Santa Ana, Albuquerque Convention Center
Helen J. Wearing, Department of Biology and Department of Mathematics & Statistics, University of New Mexico, Albuquerque, NM and Pejman Rohani, Ecology and Evolutionary Biology; Complex Systems, University of Michigan, Ann Arbor, MI
Background/Question/Methods

Case notifications of pertussis have shown an increase in a number of countries with high rates of routine pediatric immunization.  This has led to significant public health concerns over possible pertussis re-emergence.  A leading proposed explanation for the observed increase in incidence is the loss of immunity to pertussis, which is known to occur after both natural infection and vaccination. Little is known, however, about the typical duration of immunity and its epidemiological implications.  Here, we analyze a simple mathematical model, exploring specifically the inter-epidemic period and fade-out frequency.  These predictions are then contrasted with detailed incidence data for England and Wales. 
Results/Conclusions

We find model output to be most sensitive to assumptions concerning naturally acquired immunity, which allows us to estimate the average duration of immunity. Our results support a period of natural immunity that is highly variable but, on average, long-lasting (on the order of decades). We discuss the implications of these results for future work on pertussis epidemiology.

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