title: Deciphering the impacts of vaccination and immunity on pertussis epidemiology in Thailand.
abstract: Pertussis is a highly infectious respiratory disease that is currently responsible for nearly 300,000 annual deaths worldwide, primarily in infants in developing countries. Despite sustained high vaccine uptake, a resurgence in pertussis incidence has been reported in a number of countries. This resurgence has led to critical questions regarding the transmission impacts of vaccination and pertussis immunology. We analyzed pertussis incidence in Thailand--both age-stratified and longitudinal aggregate reports--over the past 30 y. To dissect the contributions of waning pertussis immunity and repeat infections to pertussis epidemiology in Thailand following a pronounced increase in vaccine uptake, we used likelihood-based statistical inference methods to evaluate the support for multiple competing transmission models. We found that, in contrast to other settings, there is no evidence for pertussis resurgence in Thailand, with each model examined pointing to a substantial rise in herd immunity over the past 30 y. Using a variety of empirical metrics, we verified our findings by documenting signatures of changing herd immunity over the study period. Importantly, this work leads to the conclusion that repeat infections have played little role in shaping pertussis epidemiology in Thailand. Our results are surprisingly emphatic in support of measurable impact of herd immunity given the uncertainty associated with pertussis epidemiology.
authors.affiliation: Department of Ecology and Evolutionary Biology and Center for the Study of Complex Systems, University of Michigan, Ann Arbor, MI 48109, USA. juliecb@umich.edu
authors.forename: Julie C
authors.initials: JC
authors.lastname: Blackwood
authors.forename: Derek A T
authors.initials: DA
authors.lastname: Cummings
authors.forename: Hélène
authors.initials: H
authors.lastname: Broutin
authors.forename: Sopon
authors.initials: S
authors.lastname: Iamsirithaworn
authors.forename: Pejman
authors.initials: P
authors.lastname: Rohani
mesh_terms: D000367:Age Factors; D001428:Bacterial Vaccines / Q000276:immunology*; D006801:Humans; D032521:Immunity, Herd / Q000276:immunology*; D015994:Incidence; D016013:Likelihood Functions; D008137:Longitudinal Studies; D018448:Models, Immunological; D013785:Thailand / Q000453:epidemiology; D014611:Vaccination / Q000706:statistics & numerical data*; D014917:Whooping Cough / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control* / Q000635:transmission*
chemical_list: D001428:Bacterial Vaccines