An outbreak of paralytic poliomyelitis occurred in the Dominican Republic (13 confirmed cases) and Haiti (8 confirmed cases, including 2 fatal cases) during 2000-2001. All but one of the patients were either unvaccinated or incompletely vaccinated children, and cases occurred in communities with very low (7 to 40%) rates of coverage with oral poliovirus vaccine (OPV). The outbreak was associated with the circulation of a derivative of the type 1 OPV strain, probably originating from a single OPV dose given in 1998-1999. The vaccine-derived poliovirus associated with the outbreak had biological properties indistinguishable from those of wild poliovirus.

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With national and global health policymakers facing numerous complex decisions related to achieving and maintaining polio eradication, we expanded our previously developed dynamic poliovirus transmission model using information from an expert literature review process and including additional immunity states and the evolution of oral poliovirus vaccine (OPV). The model explicitly considers serotype differences and distinguishes fecal‐oral and oropharyngeal transmission. We evaluated the model by simulating diverse historical experiences with polioviruses, including one country that eliminated wild poliovirus using both OPV and inactivated poliovirus vaccine (IPV) (USA), three importation outbreaks of wild poliovirus (Albania, the Netherlands, Tajikistan), one situation in which no circulating vaccine‐derived polioviruses (cVDPVs) emerge despite annual OPV use and cessation (Cuba), three cVDPV outbreaks (Haiti, Madura Island in Indonesia, northern Nigeria), one area of current endemic circulation of all three serotypes (northern Nigeria), and one area with recent endemic circulation and subsequent elimination of multiple serotypes (northern India). We find that when sufficient information about the conditions exists, the model can reproduce the general behavior of poliovirus transmission and outbreaks while maintaining consistency in the generic model inputs. The assumption of spatially homogeneous mixing remains a significant limitation that affects the performance of the differential equation‐based model when significant heterogeneities in immunity and mixing may exist. Further studies on OPV virus evolution and improved understanding of the mechanisms of mixing and transmission may help to better characterize poliovirus transmission in populations. Broad application of the model promises to offer insights in the context of global and national policy and economic models.

BackgroundThe Global Polio Eradication Initiative plans for coordinated cessation of oral poliovirus vaccine (OPV) after interrupting all wild poliovirus (WPV) transmission, but many questions remain related to long-term poliovirus risk management policies.MethodsWe used an integrated dynamic poliovirus transmission and stochastic risk model to simulate possible futures and estimate the health and economic outcomes of maintaining the 2013 status quo of continued OPV use in most developing countries compared with OPV cessation policies with various assumptions about global inactivated poliovirus vaccine (IPV) adoption.ResultsContinued OPV use after global WPV eradication leads to continued high costs and/or high cases. Global OPV cessation comes with a high probability of at least one outbreak, which aggressive outbreak response can successfully control in most instances. A low but non-zero probability exists of uncontrolled outbreaks following a poliovirus reintroduction long after OPV cessation in a population in which IPV-alone cannot prevent poliovirus transmission. We estimate global incremental net benefits during 2013–2052 of approximately $16 billion (US$2013) for OPV cessation with at least one IPV routine immunization dose in all countries until 2024 compared to continued OPV use, although significant uncertainty remains associated with the frequency of exportations between populations and the implementation of long term risk management policies.ConclusionsGlobal OPV cessation offers the possibility of large future health and economic benefits compared to continued OPV use. Long-term poliovirus risk management interventions matter (e.g., IPV use duration, outbreak response, containment, continued surveillance, stockpile size and contents, vaccine production site requirements, potential antiviral drugs, and potential safer vaccines) and require careful consideration. Risk management activities can help to ensure a low risk of uncontrolled outbreaks and preserve or further increase the positive net benefits of OPV cessation. Important uncertainties will require more research, including characterizing immunodeficient long-term poliovirus excretor risks, containment risks, and the kinetics of outbreaks and response in an unprecedented world without widespread live poliovirus exposure.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-015-1112-8) contains supplementary material, which is available to authorized users.