Polio immunization policy in the United States: a new challenge for a new generation

Optimum study of fractional polio model with exponential decay kernel

This study introduces a fractional order model to investigate the dynamics of polio disease spread, focusing on its significance, unique results, and conclusions. We emphasize the importance of understanding polio transmission dynamics and propose a novel approach using a fractional order model with an exponential decay kernel. Through rigorous analysis, including existence and stability assessment applying the Caputo Fabrizio fractional operator, we derive key insights into the disease dynamics. Our findings reveal distinct disease-free equilibrium (DFE) and endemic equilibrium (EE) points, shedding light on the disease's stability. Furthermore, graphical representations and numerical simulations demonstrate the behavior of the disease under various parameter values, enhancing our understanding of polio transmission dynamics. In conclusion, this study offers valuable insights into the spread of polio and contributes to the broader understanding of infectious disease dynamics.

Poliovirus immunizations. What goes around, comes around

Although poliovirus vaccination is nto new, the recent changes in ACIP recommendations involving polio vaccinations are. Currently, wild type poliovirus has been eliminated in the Western hemisphere, but vaccine-associated cases (VAPP) still occur. The new recommendations are intended to continue providing protection and to eliminate VAPP cases from occurring in vaccinees or close contacts.

Deterministic models for the eradication of poliomyelitis: vaccination with the inactivated (IPV) and attenuated (OPV) polio virus vaccine

Currently two polio vaccines, IPV and OPV, are in use which differ markedly in their epidemiological parameters. A simple epidemiological model in terms of ordinary differential equations is proposed to study the effects of vaccination campaigns using these vaccines. The numbers of interest are the reproduction number of the disease in the presence of vaccination and the critical vaccination coverage necessary to prevent an outbreak. For these numbers explicit representations are determined which can be used in comparing different vaccination strategies.

Using explicit decision rules to manage issues of justice, risk, and ethics in decision analysis: when is it not rational to maximize expected utility?

Concepts of justice, risk, and ethics can be merged with decision analysis by requiring the analyst to specify explicity a decision rule or sequence of rules. Decision rules are categorized by whether they consider: 1) aspects of outcome distributions beyond central tendencies; 2) probabilities as well as utilities of outcomes; and 3) means as well as ends. This formulation suggests that distribution-based decision rules could address both risk (for an individual) and justice (for the population). Rational choice under risk if choices are one-time only (vs. repeated events) or if one branch contains unlikely but disastrous outcomes might ignore probability information. Incorporating risk attitude into decision rules rather than utilities could facilitate use of multiattribute approaches to measuring outcomes. Certain ethical concerns could be addressed by prior specification of rules for allowing particular branches. Examples, including selection of polio vaccine strategies, are discussed, and theoretical and practical implications of a decision rule approach noted.

A ten-year experience in control of poliomyelitis through a combination of live and killed vaccines in two developing areas

We describe a successful program of poliomyelitis control using a combination of killed and live polio vaccines over a 10-year period in two developing areas, the West Bank and Gaza, adjacent to a relatively developed country, Israel. During the 1970s, immunization using live trivalent oral polio vaccine (OPV) in these areas covered more than 90 percent of the infant population. Nevertheless, the incidence of paralytic polio continued to be high, with many cases occurring in fully or partially immunized persons. It was thought that this could be due to interference with OPV take by other enteroviruses present in the environment due to poor sanitary conditions in these areas. A new policy combining five doses of OPV with two doses of inactivated polio vaccine (IPV) was adopted and implemented in 1978. In the 10 years since then, immunization coverage of infants increased to an estimated 95 percent and paralytic poliomyelitis has been controlled, despite exposure to wild poliovirus from neighboring countries including an outbreak in Israel in 1988. This experience suggests that wide coverage using the combination of IPV and OPV is an effective vaccination policy that may make eradication of polio possible even in developing areas.

Decision analysis and polio immunization policy

Dr. Salk's comments on our paper fall into four major categories: our use of the techniques of decision analysis, the assumptions we used, the fact that we did not include individual and social values in the model, and the way in which vaccine policies are developed in the United States. We believe that the methods were used correctly, that the assumptions we used are defensible, and that our conclusions were both appropriate and appropriately worded. We explicitly did not include individual and social values since we were addressing the scientific and epidemiologic issues rather than ethical and moral issues. Vaccine policy development in the United States is carried out in public forums with opportunity for presentation of all sides of an issue.