Introduction: Making history

In 1996 the world moved a giant step closer to eradicating polio - giving hope that future generations of children will learn of the disease from history books, never again at first hand. During that year, 420 million children - almost two thirds of the world's children under five - were immunized during mass campaigns against polio. In addition, over 80% of babies received at least three doses of oral polio vaccine during their first year of life, through routine immunization programmes.

Never before have so many children been immunized in so short a time against a single disease. This was not the end but the beginning of the end of polio. Throughout history, polio has lamed millions of people - most of them young children who had barely learned to walk. Others have died from suffocation after contracting the severest form of polio paralysis, which impedes normal breathing. Today, it is estimated that as many as 10-20 million people of all ages are living with polio paralysis. Since 1988, the World Health Organization has spearheaded global efforts to eradicate the disease by the year 2000.

In December 1996, and again in January 1997, over 250 million children were immunized against polio during coordinated national immunization days in nine countries in Asia - Bangladesh, Bhutan, China, India, Myanmar, Nepal, Pakistan, Thailand, and Viet Nam. India succeeded in immunizing 127 million children on a single day in January 1997 - the largest health event ever organized by an individual country. In India, which until recently accounted for over half the world's polio cases every year, the number of cases was slashed by 75% as a result of the massive number of children immunized during 1995 and 1996.

Earlier in the year, about 58 million children were immunized in the Middle East, Caucasus, Central Asian Republics, and Russia. This campaign - Operation MECACAR - was first conducted in 1995 to provide a coordinated onslaught on polio in 19 adjoining countries. Russia joined the campaign for the first time in 1996.

In August 1996, South African President Nelson Mandela, Chairman of the Committee for a Polio-free Africa, launched a three-year campaign - Kick Polio out of Africa. By the end of 1996, 28 African countries had carried out national immunization days, reaching over 58 million children.

Polio has been eradicated throughout the western hemisphere but the virus is still circulating in all other regions of the world.

During the final months of 1996, demand for oral polio vaccine was so great that it almost outstripped the production capacity of the major manufacturers. Although there is a large global excess production capacity for the vaccine, unforeseen delays in receiving funding for vaccine for national immunization days resulted in several last-minute orders for vaccine. In the end, none of the planned national immunization days had to be delayed, but in some countries, deliveries of vaccine often arrived only days before the launch of the campaign and had to be airlifted to immunization posts by helicopter.

As the number of countries conducting national immunization days increases - and probably peaks - during 1997 and 1998, an even larger volume of polio vaccine will be needed. Vaccine manufacturers were advised that they would need to produce almost 1.5 billion doses of the vaccine in 1997 to satisfy world demand.

It is too early to say whether polio will be eradicated on target by the year 2000. So far, the global initiative to eradicate the disease has slashed the number of cases by 90% - from over 35 000 reported cases in 1988 to less than 4000 today. Polio has been eradicated throughout the western hemisphere but the virus is still circulating in all other regions of the world. And about 100 countries are still carrying out mass immunization campaigns in addition to routine immunization against polio.

The final stages of polio eradication are expected to be the most difficult. The countries where polio is still endemic include some of the poorest countries in the world. Many are unable to reach the majority of their population with even basic health services. In some, health infrastructures have been destroyed by war and neglect, vaccine supply lines cut off, and immunization programmes suspended - setting the stage for an upsurge in polio and other vaccine- preventable diseases. Despite the success of a number of negotiated ceasefires for immunization, children become difficult to reach when conflict erupts. War-related outbreaks of polio occurred in Chechnya in the Russian Federation in 1995, in Iraq (1992-93), and in Sudan (1993). Today, emerging polio-free areas are threatened by continuing political unrest in Afghanistan, Angola, Congo, Democratic Republic of Congo, Iraq, Liberia, Sierra Leone, Somalia, and Sudan.

Donor fatigue and the competing need for funds to combat other infectious diseases - some both more life-threatening and more widespread than polio - pose continuing threats to the eradication of polio. Pneumonia, diarrhoea, measles, and malaria together kill about eight million children a year. And many of these deaths occur in the poorest countries - including those where polio is still endemic.

The danger is that, as the number of polio cases continues to fall and the risk of infection recedes, people will become complacent about polio and let their guard down - enabling the disease to stage a comeback. Both donors and cash-strapped governments may be less willing to spend millions of dollars a year on polio eradication when very few cases are occurring. But without adequate donor funding and high-level political commitment to polio eradication in the poorest developing countries, poliovirus will continue to circulate - both in those countries and beyond. And unless the polio-free countries continue to maintain high routine immunization coverage, there is a risk that polio could be re-established in those countries through importation of the virus from a polio-endemic country.

Other constraints include vaccine shortages during periods of political and economic transition, and the need to raise at least US$ 800 million altogether - if polio is to be eradicated as planned by the turn of the century.

In the 1940s and 1950s “iron lungs” were used to regulate breathing and keep polio patients alive.

Photo: WHO (1669)