The latter two situations are plainly the most interesting. If eradication were a coordination game, we could not rely on unilateralism alone to sustain the better equilibrium, but nor would the demands on the international system be very great. To have an incentive to eliminate, each country would need only to be assured that all other countries would eliminate. The distinction is crucial, because WHO lacks the power of enforcement. Article 21 of the WHO Constitution authorizes the Organization to adopt regulations "designed to prevent the international spread of disease," but it does not permit punishment of states that fail to comply; and in the entire history of WHO, Article 21 has been invoked only twice WHO has instead relied on making recommendations that can only be enforced by means of moral persuasion.
In the past, these efforts have largely failed 15 , though the Organization's response to the SARS outbreak marked a dramatic turn. By issuing travel alerts, and then subsequently being given the formal approval to do so, WHO has essentially extended its authority What we do not yet know is whether this new authority will extend to other areas.
Contributing to the eradication, elimination and control of some infectious diseases - Sanofi
The circumstances of SARS were special: it was and remains a huge threat, partly because everyone in the world is susceptible and partly because there is no vaccine to protect against infection. What were the economics of smallpox eradication for individual countries? Rich countries gained tremendously.
Poor countries also gained. Rich countries, of course, eliminated smallpox even before the eradication initiative was launched, whereas many poor countries did not. But this failure to eliminate was not for a lack of incentives. It was rather a consequence of administrative failings. They simply lacked the technical and managerial expertise needed to achieve the goal 6.
For this reason, smallpox eradication required international cooperation and not only coordination. The way in which this was achieved is explained in the next section. How does the geography of control differ from that of eradication? Disease control is a strategic substitute. As one country increases its control of a disease, other countries have an incentive either not to change their control policies or to decrease control.
This is because control by one country reduces the risk of importing infections, and as the risk of imports falls, so does the local incentive to control the disease. The Nash equilibrium of the disease control game is thus likely to be characterized by too little control overall. Improvements in this situation would likely make all countries better off at least all countries that control to a level short of elimination , but implementation of a global programme for control would also require enforcement, which, as noted before, is a potential problem.
Rather than promote control directly, it may be better to lower the cost of vaccination perhaps through bulk purchases of vaccines. Doing this would increase the incentive to control and so increase control indirectly. Financing eradication versus control. For example, many industrialized countries have eliminated measles within their borders, whereas measles kills about children a year in developing countries. Since elimination protects high-income countries from imports, they cannot gain directly by financing control in developing countries.
Offers by high-income countries to finance measles control would essentially constitute aid. Eradication is different. If poor countries were unable to eliminate a disease on their own or as part of a coordinated effort, or if they lacked the incentive to do so, rich countries might have an incentive to finance a global eradication programme. In doing so, rich countries would earn a return on their investment the eradication dividend , while poor countries would also become better off. Rich countries would not need to pay the entire cost.
Poor countries are likely to have some incentive to control a disease on their own. Rich countries would need only pay the cost of reducing incidence from the current level which may already be low, depending on the poor country's own incentives to control to 0. Indeed, this is precisely how the smallpox eradication campaign was financed 6. Rich countries paid only about a third of the total cost of eliminating smallpox from developing countries.
In the current effort to eradicate polio even the poorest countries pay between a quarter and a half of the costs of local implementation 5. Of course, this is not to say that the United States would necessarily be the only contributor. Indeed, other countries did contribute to the smallpox eradication effort.
However, because the United States would do better by financing the entire effort even if other countries contributed nothing, we can be sure that eradication must have been a Nash equilibrium. This is an encouraging observation, for it tells us that eradication can be supported even by the anarchic international system. However, financing for the smallpox eradication campaign proved miserly. While the United States contributed more than any other country, financing requirements were only met after other countries especially Sweden stepped into the breach.
There are two likely explanations for the difficulty in raising finance internationally First, while a country like the United States had an incentive to finance the entire eradication effort even if no other country did so, it may have been reluctant to pay the entire bill, partly in the hope, and perhaps expectation, that others would contribute and partly because of the belief that, since the benefits of eradication would be shared, the costs ought to be shared too.
Second, though eradication promised huge net benefits to individual countries, the gains would be diffused internally. Though no political constituency would oppose eradication, none would necessarily lobby strongly for it either. Any past expenditure on polio eradication is discounted, and therefore irrelevant to any decision to eradicate that starts from today.
In present value terms, the benefit of eradication to the United States would be about 33 times this value. Hence, it appears that if countries are able to stop vaccinating, then polio eradication would be a Nash equilibrium and so would be achievable by existing international institutions. This situation is similar to the earlier smallpox experience, but there are three important differences.
First, support from Rotary International and other foundations lowered the cost to governments of financing the effort. Second, the involvement of these organizations also provided domestic political pressure for enhanced state financing. Finally, the polio eradication initiative learned from the smallpox experience and professionalized its approach to fund-raising 5. Compared to control, eradication of a vaccine-preventable infectious disease is a high-risk goal but one that also has a number of advantages. Aggregate welfare is maximized either when a disease is controlled at a relatively low level or when it is eradicated.
Control at a very high level will not be globally optimal in the sense of maximizing the present value sum of net benefits when eradication is feasible. Diseases already controlled at a very high level in rich countries are thus prime candidates from the perspective of economics for global eradication. The eradication of these diseases would benefit the rich countries substantially and so make it attractive for them to finance a global effort.
The international system is not well suited to implementing interventions that require enforcement, but this failing helps to make eradication an attractive policy goal. In some cases, eradication will require only coordination among countries. In other cases, cooperation will be required, but the binary nature of eradication as contrasted with control , coupled with the strong asymmetry between rich countries and poor countries, helps make full financing of an eradication effort compatible with the self interests of states even without international enforcement.
The smallpox experience teaches that full financing is not guaranteed, but the polio campaign shows how strategies and tactics can be used to improve the campaign's chances of success.
I am grateful to Julia Fox-Rushby for inviting me to the workshop; to the workshop participants, and especially my discussant, Alastair Gray, for helpful comments on an earlier version of this paper; to D. Henderson for illuminating discussions on the history of the smallpox eradication effort; to Bruce Aylward for very helpful comments on an earlier draft and for several follow-up conversations; and to two anonymous reviewers for further comments.
Conflicts of interest: none declared. Oxford: Oxford University Press; Roberts L. Polio: the final assault? Science ; Hinman A. Eradication of vaccine-preventable diseases. American Review of Public Health ; Lederberg J. Summary and assessment. Considerations for viral disease eradication: lessons learned and future strategies.
Polio eradication. Global public goods for health: health economic and public health perspectives. Smallpox and its eradication.
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The Principles of Disease Elimination and Eradication
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