Limits...
Estimating the extent of vaccine-derived poliovirus infection.

Wringe A, Fine PE, Sutter RW, Kew OM - PLoS ONE (2008)

Bottom Line: Although only 114 virologically-confirmed paralytic cases were identified in the eight cVDPV outbreaks, it is likely that a minimum of hundreds of thousands, and more likely several million individuals were infected during these events, and that many thousands more have been infected by VDPV lineages within outbreaks which have escaped detection.Our estimates of the extent of cVDPV circulation suggest widespread transmission in some countries, as might be expected from endemic wild poliovirus transmission in these same settings.These methods for inferring extent of infection will be useful in the context of identifying future surveillance needs, planning for OPV cessation and preparing outbreak response plans.

View Article: PubMed Central - PubMed

Affiliation: Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, England. alison.wringe@lshtm.ac.uk

ABSTRACT

Background: Eight outbreaks of paralytic polio attributable to circulating vaccine-derived poliovirus (cVDPV) have highlighted the risks associated with oral poliovirus vaccine (OPV) use in areas of low vaccination coverage and poor hygiene. As the Polio Eradication Initiative enters its final stages, it is important to consider the extent to which these viruses spread under different conditions, so that appropriate strategies can be devised to prevent or respond to future cVDPV outbreaks.

Methods and findings: This paper examines epidemiological (temporal, geographic, age, vaccine history, social group, ascertainment), and virological (type, genetic diversity, virulence) parameters in order to infer the numbers of individuals likely to have been infected in each of these cVDPV outbreaks, and in association with single acute flaccid paralysis (AFP) cases attributable to VDPVs. Although only 114 virologically-confirmed paralytic cases were identified in the eight cVDPV outbreaks, it is likely that a minimum of hundreds of thousands, and more likely several million individuals were infected during these events, and that many thousands more have been infected by VDPV lineages within outbreaks which have escaped detection.

Conclusions: Our estimates of the extent of cVDPV circulation suggest widespread transmission in some countries, as might be expected from endemic wild poliovirus transmission in these same settings. These methods for inferring extent of infection will be useful in the context of identifying future surveillance needs, planning for OPV cessation and preparing outbreak response plans.

Show MeSH

Related in: MedlinePlus

The distribution of reported cVDPV cases in Egypt (grey bars) is shown on the left hand axis. The estimated number of infections (dotted line) between 1983 (when the initiating infection is estimated to have occurred) and the end of the outbreak is plotted against the right hand axis, and represents a best estimate of the distribution of infections.The approximation for the number of infections is represented by the area under the curve, and assumes a constant case to infection ratio of 1∶1000, and average case ascertainment of ∼10%.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2570794&req=5

pone-0003433-g007: The distribution of reported cVDPV cases in Egypt (grey bars) is shown on the left hand axis. The estimated number of infections (dotted line) between 1983 (when the initiating infection is estimated to have occurred) and the end of the outbreak is plotted against the right hand axis, and represents a best estimate of the distribution of infections.The approximation for the number of infections is represented by the area under the curve, and assumes a constant case to infection ratio of 1∶1000, and average case ascertainment of ∼10%.

Mentions: The neurovirulence of two isolates from the outbreak was measured in transgenic mice and found to be similar to the prototype wild type 2 strain[1]. Assuming a case-to-infection ratio for wild type 2 of 1∶1,000, the 30 reported cases alone are likely to be associated with around 30,000 infections (figure 7).


Estimating the extent of vaccine-derived poliovirus infection.

Wringe A, Fine PE, Sutter RW, Kew OM - PLoS ONE (2008)

The distribution of reported cVDPV cases in Egypt (grey bars) is shown on the left hand axis. The estimated number of infections (dotted line) between 1983 (when the initiating infection is estimated to have occurred) and the end of the outbreak is plotted against the right hand axis, and represents a best estimate of the distribution of infections.The approximation for the number of infections is represented by the area under the curve, and assumes a constant case to infection ratio of 1∶1000, and average case ascertainment of ∼10%.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2570794&req=5

pone-0003433-g007: The distribution of reported cVDPV cases in Egypt (grey bars) is shown on the left hand axis. The estimated number of infections (dotted line) between 1983 (when the initiating infection is estimated to have occurred) and the end of the outbreak is plotted against the right hand axis, and represents a best estimate of the distribution of infections.The approximation for the number of infections is represented by the area under the curve, and assumes a constant case to infection ratio of 1∶1000, and average case ascertainment of ∼10%.
Mentions: The neurovirulence of two isolates from the outbreak was measured in transgenic mice and found to be similar to the prototype wild type 2 strain[1]. Assuming a case-to-infection ratio for wild type 2 of 1∶1,000, the 30 reported cases alone are likely to be associated with around 30,000 infections (figure 7).

Bottom Line: Although only 114 virologically-confirmed paralytic cases were identified in the eight cVDPV outbreaks, it is likely that a minimum of hundreds of thousands, and more likely several million individuals were infected during these events, and that many thousands more have been infected by VDPV lineages within outbreaks which have escaped detection.Our estimates of the extent of cVDPV circulation suggest widespread transmission in some countries, as might be expected from endemic wild poliovirus transmission in these same settings.These methods for inferring extent of infection will be useful in the context of identifying future surveillance needs, planning for OPV cessation and preparing outbreak response plans.

View Article: PubMed Central - PubMed

Affiliation: Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, England. alison.wringe@lshtm.ac.uk

ABSTRACT

Background: Eight outbreaks of paralytic polio attributable to circulating vaccine-derived poliovirus (cVDPV) have highlighted the risks associated with oral poliovirus vaccine (OPV) use in areas of low vaccination coverage and poor hygiene. As the Polio Eradication Initiative enters its final stages, it is important to consider the extent to which these viruses spread under different conditions, so that appropriate strategies can be devised to prevent or respond to future cVDPV outbreaks.

Methods and findings: This paper examines epidemiological (temporal, geographic, age, vaccine history, social group, ascertainment), and virological (type, genetic diversity, virulence) parameters in order to infer the numbers of individuals likely to have been infected in each of these cVDPV outbreaks, and in association with single acute flaccid paralysis (AFP) cases attributable to VDPVs. Although only 114 virologically-confirmed paralytic cases were identified in the eight cVDPV outbreaks, it is likely that a minimum of hundreds of thousands, and more likely several million individuals were infected during these events, and that many thousands more have been infected by VDPV lineages within outbreaks which have escaped detection.

Conclusions: Our estimates of the extent of cVDPV circulation suggest widespread transmission in some countries, as might be expected from endemic wild poliovirus transmission in these same settings. These methods for inferring extent of infection will be useful in the context of identifying future surveillance needs, planning for OPV cessation and preparing outbreak response plans.

Show MeSH
Related in: MedlinePlus