Pertussis immunity and epidemiology: mode and duration of vaccine-induced immunity.
The resurgence of pertussis in some countries that maintain high vaccination coverage has drawn attention to gaps in our understanding of the epidemiological effects of pertussis vaccines. In particular, major questions surround the nature, degree and durability of vaccine protection. To address these questions, we used mechanistic transmission models to examine regional time series incidence data from Italy in the period immediately following the introduction of acellular pertussis (aP) vaccine. Our results concur with recent animal-challenge experiments wherein infections in aP-vaccinated individuals proved as transmissible as those in naive individuals but much less symptomatic. On the other hand, the data provide evidence for vaccine-driven reduction in susceptibility, which we quantify via a synthetic measure of vaccine impact. As to the precise nature of vaccine failure, the data do not allow us to distinguish between leakiness and waning of vaccine immunity, or some combination of these. Across the range of well-supported models, the nature and duration of vaccine protection, the age profile of incidence and the range of projected epidemiological futures differ substantially, underscoring the importance of the remaining unknowns. We identify key data gaps: sources of data that can supply the information needed to eliminate these remaining uncertainties.
Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA.
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Magpantay
Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA.
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Domenech DE Cellès
Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA.|Center for the Study of Complex Systems, University of Michigan, Ann Arbor, MI 48109, USA.|Fogarty International Center, National Institutes of Health, Bethesda, MD 20892, USA.
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Rohani
Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA.|Center for the Study of Complex Systems, University of Michigan, Ann Arbor, MI 48109, USA.|Fogarty International Center, National Institutes of Health, Bethesda, MD 20892, USA.|Department of Mathematics, University of Michigan, Ann Arbor, MI 48109, USA.
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King
D017677:Age Distribution; D016208:Databases, Factual; D006801:Humans; D007109:Immunity / Q000276:immunology*; D015994:Incidence; D007558:Italy / Q000453:epidemiology; D008954:Models, Biological; D010567:Pertussis Vaccine / Q000276:immunology*; D013997:Time Factors; D014917:Whooping Cough / Q000453:epidemiology* / Q000276:immunology* / Q000517:prevention & control / Q000635:transmission
D010567:Pertussis Vaccine
disease dynamics; imperfect vaccine; iterated filtering; leaky vaccine; likelihood-based inference; pertussis; waning immunity