Expert Review on Poliovirus Immunity and Transmission

Successfully managing risks to achieve wild polioviruses (WPVs) eradication and address the complexities of oral poliovirus vaccine (OPV) cessation to stop all cases of paralytic poliomyelitis depends strongly on our collective understanding of poliovirus immunity and transmission. With increased shifting from OPV to inactivated poliovirus vaccine (IPV), numerous risk management choices motivate the need to understand the tradeoffs and uncertainties and to develop models to help inform decisions. The U.S. Centers for Disease Control and Prevention hosted a meeting of international experts in April 2010 to review the available literature relevant to poliovirus immunity and transmission. This expert review evaluates 66 OPV challenge studies and other evidence to support the development of quantitative models of poliovirus transmission and potential outbreaks. This review focuses on characterization of immunity as a function of exposure history in terms of susceptibility to excretion, duration of excretion, and concentration of excreted virus. We also discuss the evidence of waning of host immunity to poliovirus transmission, the relationship between the concentration of poliovirus excreted and infectiousness, the importance of different transmission routes, and the differences in transmissibility between OPV and WPV. We discuss the limitations of the available evidence for use in polio risk models, and conclude that despite the relatively large number of studies on immunity, very limited data exist to directly support quantification of model inputs related to transmission. Given the limitations in the evidence, we identify the need for expert input to derive quantitative model inputs from the existing data.     

Explaining costumer reactions to real stockouts

The occurrence of stockouts remains an unsolved problem for retailers that provoke severe revenue and image losses, as well as greater customer dissatisfaction for both retailers and manufacturers. A literature review suggests a model of influential antecedents of consumers’ reactions to product unavailability. A field study then provides insights into true stockout situations, unlike a hypothetical research setting. With these data, this study reveals that loyalty and the presence of product alternatives have the greatest impacts on customer reactions. This result has significant theoretical and managerial implications due to the fact that results based on hypothetical settings did not hold.     

Agency conflicts between board and manager

Detecting agency problems is an important task when assessing the effectiveness of a nonprofit organization's governance. A first step is to examine the objectives of principals and agents and determine whether there is a systematic difference between them. Using a discrete choice experiment, we identify the objectives of board chairpersons (principals) and headmasters (agents) of Flemish nonprofit schools. We find systematic differences between the two groups. Of the seven possible objectives set out in the experiment, six are relevant for both headmasters and board chairpersons. For four of these, the preferences of both groups differ significantly. Whereas ideological values play an important role for both the board and the headmaster, they are significantly more important for the board. Both parties dislike having a large number of pupils, and the disutility is larger for the board. With respect to job satisfaction and pupil satisfaction, we find the opposite: while the board is prepared to give up pupil and job satisfaction in favor of the other objectives, these two objectives score very high on the priority list of the headmasters.     

Risks of Paralytic Disease Due to Wild or Vaccine-Derived Poliovirus After Eradication

After the global eradication of wild polioviruses, the risk of paralytic poliomyelitis from polioviruses will still exist and require active management. Possible reintroductions of poliovirus that can spread rapidly in unprotected populations present challenges to policymakers. For example, at least one outbreak will likely occur due to circulation of a neurovirulent vaccine-derived poliovirus after discontinuation of oral poliovirus vaccine and also could possibly result from the escape of poliovirus from a laboratory or vaccine production facility or from an intentional act. In addition, continued vaccination with oral poliovirus vaccines would result in the continued occurrence of vaccine-associated paralytic poliomyelitis. The likelihood and impacts of reintroductions in the form of poliomyelitis outbreaks depend on the policy decisions and on the size and characteristics of the vulnerable population, which change over time. A plan for managing these risks must begin with an attempt to characterize and quantify them as a function of time. This article attempts to comprehensively characterize the risks, synthesize the existing data available for modeling them, and present quantitative risk estimates that can provide a starting point for informing policy decisions.     

Affirmative action in winner-take-all markets

Whom to hire, promote, admit into elite universities, elect, or issue government contracts to are all determined in a tournament-like (winner-take-all) structure. This paper constructs a simple model of pair-wise tournament competition to investigate affirmative action in these markets. We consider two forms of affirmative action: group-sighted, where employers are allowed to use group identity in pursuit of their diversity goals; and group-blind, where they are not. It is shown that the equilibrium group-sighted affirmative action scheme involves a constant handicap given to agents in the disadvantaged group. Equilibrium group-blind affirmative action creates a unique semi-separating equilibrium in which a large pool of contestants exerts zero effort, and this pool is increasing in the aggresiveness of the affirmative action mandate.