Summary This paper analyzes the conditions for eradication of diseases in a static and dynamic framework. In static framework, it investigates whether it is possible to eradicate diseases. There has been controversy in the public health research as to the possibility of eradication of diseases. Although epidemiologists have always felt that eradication of disease possible, there has been suspect amongeconomists. A representative view of the suspect has been reported in the Hand Book of Health economics as “…although the introduction of a vaccine usually produces a sharp drop in the occurrence of a disease, the eradication of vaccine preventable diseases predicted by many at the time of these inventions has not been achieved except for smallpox. Of the roughly forty vaccines on the market, only thesmallpox vaccine has eradicated its target disease. Diseases … persist, despite explicit governmental efforts to eradicate them, and recent attempts to develop a vaccine against HIV or AIDS raise important questions about the causes behind these difficulties…”
Revisiting the economics behind possibility of disease eradication instatic framework, it seems that given the necessary economic incentives are fulfilled, in contrast to some of the recent literature; the results imply that it is possible to eradicate diseases, at least those whose dynamics follows Susceptible-Infective- Recovery, SIR framework. Individuals choose the level of vaccination that ensures eradication if the full cost of the vaccine that accrue to the individual is subsidized.
By expanding the framework to dynamic analysis, in the SIR models of infectious diseases, it tries to see whether there is biological limitation to eradication of infectious diseases. The canonical model of human disease dynamics imply that given certain critical level of vaccination is satisfied, it is possible to eradicatediseases. Given biological conditions are met and economic incentives are satisfied, unlike the suspect of some economists, it is possible to eradicate diseases.
Knowing that it is possible to eradicate infectious diseases, the social planner may resort to various public health policies including doing nothing, controlling, eliminating, eradicating or extinctions of diseases. But in order to make the choice of policies simpler, this paper considers two policies, namely doing nothing versus eradication, and considers them in their extreme version in light of economic benefits. It compares whether eradicating as fast as possible is preferable to doing nothing. The ultimate comparison involves choosing between the discounted cost of infection if the disease is left uninterrupted by deliberate policy measures and the discounted cost eradicating the disease as fast as possible. In relation to economic optimality, it has been shown that, in thelimiting case where the ratio of terminal to initial infection approaches zero, eradicating as fast as possible is preferred to doing nothing when the discounted cost of infection of the fraction of initial population infected is greater than the unit cost of vaccination.
Depending on the parametric values, some diseases could be candidate for eradication and others may not be. Especially it seems that the cost benefit rule looks more sensitive to the ratio of the maximum fraction of infected people in which the disease can’t expand to the equilibrium fraction of infected people if the disease is left uninterrupted. The cost benefit rule suggests fewer diseases tobe eradicated as the ratio of terminal rate of infection to initial rate of infection approaches zero. In this regard the paper is in center view of epidemiologists that suggest eradication of most diseases and suspicious economists that suggest diverting our attention fully from eradication.
Finally, there has been some effort committed to see whether the current global action to eradicate polio is economically preferable. The results that follow from the cost benefit rule suggest that eradicating polio even using oral live-attenuated polio vaccine [OPV] is not optimal in both rich and poor countries.