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Polio Vaccinations End?
Scientists declared the Western Hemisphere "polio-free" in 1994; two years later, only 4,000 cases were reported worldwide. Wild polio virus has been largely confined to South Asia and Africa; complete eradication of the disease is expected by 2003.
As a result, World Health Organization (WHO) officials are now exploring strategies for bringing an end to polio vaccinations.
In a "Policy Forum" in the August 8 issue of Science, one pair of scientists at WHO in Geneva and another pair at Columbia University College of Physicians and Surgeons in New York square off on some of the issues involved.
This policy debate comes less than one month before a planned September 1997 meeting convened by WHO to draft "a plan for containment procedures that will be widely circulated in the scientific community before implementation."
The Columbia scientists, A.W. Dove and V.R. Racaniello, question whether it will ever be possible to end polio vaccination.
"In the post-vaccine world, the susceptible population would increase each year and the large number of potential sources of reintroduction would soon constitute a major threat." Basing their calculations on a 1992-93 Dutch epidemic, they roughly estimate the magnitude of the threat this way: "In a city of 10 million unvaccinated individuals ... a single release of virus could result in 7000 paralytic cases."
Harry F. Hull and R.B. Aylward at WHO question the view that there is too great a potential for polio persistence with the use of live vaccine.
and Aylward conclude, "Halting the use of OPV remains the simplest
and most cost-efficient means for stopping immunization. This option
should not be abandoned without compelling reasons to do so."
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