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Ending polio - now or never?

By Jong Wook Lee

Dr. Jong Wook Lee is Director of the Global Programme for Vaccines and Immunization, WHO. Until 1994, he was Team Leader of the Polio Eradication Initiative in the Western Pacific Regional Office of WHO.

Under the impact of a 20-year effort, polio is in retreat. World-wide, the estimated number of cases has fallen from 400,000 in 1980 to just over 100,000 in 1993. Of 213 countries under surveillance, 145 reported zero cases in 1993.

Confidence is therefore running high that the goal of eradicating polio by the year 2000 will be met.

Such confidence is dangerous.

Polio cannot be eradicated anywhere until it is eradicated everywhere. And as the following pages show, there are some 68 countries in which wild polio virus is still circulating. Some of those countries - Bangladesh, India, Pakistan - are among the largest and poorest. Others, like Ethiopia or Nigeria, have weak health infrastructure. One or two, like Myanmar, have not so far shown a real commitment to polio eradication. Still others, such as Azerbaijan and Uzbekistan, are witnessing new polio outbreaks as health systems deteriorate. And in many nations, from Afghanistan to Rwanda, the effort is being sabotaged by conflicts and their aftermath.

Adding to these difficulties, some of the donor nations are dragging their feet.

No hiding-place

Stage one on the road to eradication is a high level of routine coverage with oral polio vaccine (OPV). This reduces polio to low levels.

Stage two involves blitzing the virus in a series of national immunization days, during which all under-fives are given two doses of OPV. This immunizes those missed by routine coverage, and boosts the immunity of the already vaccinated. So far, 58 countries have held national immunization days. In 1994, for example, China reached 83 million children in just two days.

After this, the polio virus has few hiding-places (it cannot live for more than a few months without a human host). And the stage is now set for the final act.

Stage three demands a change in approach. Every suspected case of polio must now be detected by national surveillance systems backed by laboratories. If paralysis is found to be caused by wild polio virus (other viruses can mimic polio), then a supplementary immunization effort must be targeted to the outbreak.

In this way, the last hiding-places of the infection are discovered and eliminated.

If the effort to eradicate polio is to fail, then it will fail here at this final stage.

Large quantities of vaccine are needed and the surveillance systems, especially the laboratories, can be expensive. Meanwhile pneumonia, diarrhoeal disease, malaria, AIDS, are afflicting large numbers. Why should countries devote several million dollars to eradicating a virus which now affects only a handful of children a year?

No doubt people will say that the year 2000 is only a symbolic date, and that it doesn't really matter whether eradication is achieved in 2000, or 2005 or 2010. But this is an even more dangerous fallacy.

To see why, let us place ourselves at some date early in the next century. Polio has been almost but not quite eradicated. Very few cases are occurring. And it is now almost impossible for countries to continue devoting millions of dollars a year to the few remaining cases. The perceived threat has faded. And so has the political momentum. Donor countries cannot be persuaded to keep up the funding. With the momentum lost, even routine immunization levels may begin to fall.

Meanwhile the very low incidence of polio means an ever-increasing population of young people who are neither vaccinated nor immune through natural infection (most cases of polio are mild, with no long-term consequences).

In this way, the potential for a polio epidemic slowly builds up in the early years of the next century.

When that epidemic breaks it will be more difficult to cope with. The large pool of unprotected children will include older children (for whom polio is usually more serious), and efforts to surround outbreaks may then have to be aimed not just at under-fives but at the much larger group of under-tens or even under- fifteens.

Secondly, 'failure' will make it harder to mount another eradication attempt. Remember the effort to wipe out malaria? When it failed, mobilizing support for further attempts at malaria control became almost impossible.

Eradicating polio requires a head of steam. This we now have. But if the year 2000 target is not achieved, then that pressure will quickly be lost. We will have to start with cold water all over again.

It is therefore not a case of 'if not by the year 2000, then soon after'. Indeed, it may well be a case of 'now or never'.

Pioneering

The case for seizing the present opportunity to eradicate polio goes deeper than this. In particular, its cost-effectiveness needs to be weighed in a wider scale.

First of all, polio eradication is integrated into the worldwide vaccination programme, strengthening and being strengthened by the effort to build immunization systems. Second, it pioneers a path for bringing other major diseases under control, from measles to pneumonia. In the years ahead, there will be an increasing need to shift from 'input' approaches to 'outcome' approaches - from service coverage to ever more competent epidemiology. This requires different skills and strategies - which can be 'learned by doing' in the final stages of polio eradication.

More intangibly, eradication would boost morale. Success breeds success. And another famous victory would help to motivate the millions who wage the daily struggle for health throughout the world.

Economics

Finally, eradication makes obvious economic sense.

If the world remains in the limbo of the 'nearly but not quite' stage of polio eradication, then vaccination will have to be maintained in all countries. If eradication is achieved, all countries can cease vaccination.

Polio immunization costs about $270 million a year in the United States and about $200 million a year in Western Europe. The cost for the world as a whole is many times greater. The effort to eradicate polio would therefore pay for itself within a relatively short time - just as the eradication of smallpox has paid for itself many times over in the last two decades.

The last stage of this struggle will be difficult, particularly in countries affected by conflict. But it is reasonable to suggest that the industrialized nations should ensure funding. For it is to the industrialized nations that the greatest savings will accrue. The total amount of external aid needed over the final five years of this effort will be approximately $130 million a year. The United States alone will save twice that much every year once the virus is gone.

The savings to the developing countries will also be significant. Only in the short term, therefore, is polio eradication competing for scarce health resources. Once achieved, it will actually release resources for the struggle against other threats to human health.

Following the victory over smallpox in the 1970s, there is now no doubt that polio can become the second major disease to be banished from the earth. We have the technologies and the strategies. At the present time, we also have the momentum. And it would be a tragedy if it does not carry us through to a final victory over poliomyelitis.


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