Target 2000

6 Target 2000 Nicholas Ward & Harry Hull The goal: to immunize as many infants as possible. Wen, in 1988, the World Health Assembly estab-lished the year 2000 as the target for global poliomyelitis eradi- cation, a period of 12 years was allotted to accomplish that goal. As 1995 begins, more than half that time has elapsed and it is appropriate to examine the progress that has been achieved and what remains to be ac- complished if we are to wipe out the naturally occurring or "wild" polio- virus within the next five years. The strategies for polio eradica- tion recommended by WHO are simple in concept. Firstly, to support routine immunization systems and immunize as many infants as possi- ble with 3-4 doses of oral polio vaccine (OPV) . High routine cover- age reduces the incidence of polio to low levels and forms the base for the polio eradication initiative. Third- dose (OPV3) coverage rose rapidly during the 1980s, and WHO esti- mates that 80% of infants born in 1993 have been immunized with three doses of OPV. The second polio eradication strategy is to conduct national immu- nization days. These campaigns ad- minister two doses ofOPV to all children under five, in- cluding those who have previously received the basic course of immunization. The object is to stop the spread of wild poliovirus by boosting the immunity of children who have already been vaccinated and by immunizing chil- dren not reached by routine services. As the virus cannot live for long peri- ods outside the human body, national immunization days effectively remove the wild poliovirus from countries where the disease is endemic. The third strategy is to establish extremely sensitive surveillance sys- tems, capable of detecting every last case of poliomyelitis in a country. Because other paralytic conditions can mimic polio, stool specimens are collected from all children with acute flaccid paralysis. These stool speci- mens are then tested in certified laboratories to determine if the paral- ysis is caused by wild poliovirus. The final strategy is to use surveillance data to plan and carry out localized immunization campaigns, targeting high-risk districts where the last few cases of polio occur. In these "mopping-up" campaigns, OPV is taken from door to door, and two doses are adminis- tered to all children under five. World Health • 48th Yeor, No. 1, Jonuory-Februory 1995 Rapid decline in cases As these strategies have been suc- cessfully undertaken by more and more countries, the number of cases is declining rapidly and the wild poliovirus is being confined to a geographically restricted area of the world. The number of cases reported in 1993 by WHO 's Member States was only 9164. This is a 74% de- cline from the 35 225 cases reported to WHO in 1988. Six "emerging polio-free zones" have been identified where the wild virus has either disappeared or is at such a low level that eradication could be rapidly achieved. These zones are: The Americas, Western and Central Europe, North Africa, the Middle East, Southern and East Africa, and the Western Pacific. West and Central Africa and South Asia are the principle reservoirs of wild poliovirus. In the American Region, it is more than three years since the last case occurred in the entire Western Hemisphere, affecting a two-year-old boy from Peru who was paralysed in August 1991. The Region has been certified free of wild virus, but chil- dren are still being immunized to prevent any spread if the virus should be reintroduced from other conti- nents. Although much has been accom- plished and there are many reasons to be confident that Target 2000 will be achieved, global polio eradication is far from assured. What are the major obstacles to be overcome if we are to reach the goal? First among these is insufficient political commitment. World Health • 48th Year, No. 1, Jonuary-Februory 1995 The World Health Assembly estab- lished the polio eradication target in 1988 and reaffirmed that commitment in 1993. UNICEF and more than 130 world leaders adopted the same goal at the World Summit for Children in 1990. Yet sufficient support to achieve the goal is only beginning to materialize. Rotary International, in particular, is to be commended for its advocacy efforts on behalf of polio eradication. But if global eradication is to be achieved, all polio-endemic countries will need to make the commitment to eradica- tion at the highest levels. Since the benefits of polio eradi- cation will accrue to all countries , additional financing for the initiative should be provided by both industri- alized countries and the international donor agencies. Additional political commitment and expanded external funding will be particularly impor- tant as each year passes, for as the target approaches, wild poliovirus will exist only in the least vigilant countries and the most difficult regions within those countries. Financing the initiative remains problematic. The most recent estimate of the total external cost of polio eradication is more than $800 million, nearly two-thirds of which is for the purchase of oral polio vaccine. If funds are available, cur- On National Immunization Day, every child receives the life-saving "polio drop". rent production capacity is sufficient to manufacture all the vaccine needed, but additional funds for vac- cine purchase are still needed. Global immunization coverage peaked in 1990 when 85% of infants born that year had received three or more doses of OPV; since then there has been a gradual decline in immu- nization coverage for all vaccines. The combination of falling coverage and low disease incidence results in a rapidly increasing population of chil- dren who have not been vac-cinated but are also not immune through nat- ural infection. Political upheavals, economic change, social unrest and war pose constant threats to the Polio Eradication Initiative. If the world unites to provide the additional financial resources, per- sonnel and vaccine needed, all these obstacles can and will be overcome. We can then look forward to the day when parents need no longer fear that their child will be crippled by poliomyelitis. • Or Nicholas Ward and Dr Harry Hull are with the Expanded Programme on Immunization, Global Programme for Vaccines and Immun ization , World Health Organization, 121 1 Geneva 27, Switzerland Eradication approaching in China The front lines of the global war aga inst pol iomyelitis have sh ifted from South America to As ia. The battle has been fierce in the world's most popu lous nation, China, but polio is now in full retreat, and there are high hopes that w ild vi rus transmission w il l be stopped in time to meet China's 1995 eradication goal. Thanks to the excellent primary health care system, pol io seemed to be disappearing from China when the globa l eradication target was establ ished. Widespread epidemics wi th some 5000 cases in both 1989 and 1990 dimmed hopes, but Ch ina has fought back. Provincial-level immunization days in 199 1 and 1992 set the stage for the world's largest public health events - national immunization days held a year ago and currently being repeated this winter. The resu lt of these campaig ns has been a rapid decline in the pol io cases reported- only 653 in 1993 . More revea ling is evidence provided by laboratory-based virological survei llance. Wild pol iovi rus was fou nd in seven out of 30 prov inces in 1993 and in only one province during the first ha lf of 1994 . The seven provinces were ta rgeted for final-stage immunizations last autumn. Pl a nning the final assault on pol io requires accurate, timely knowledge abou t the last chains of virus transm ission , obta inable only by cul turing stool specimens from every paralysed ch ild in the country. Virology laboratories in most provinces lack essentia l supplies and work with outdated equipment. A coalition of donors, led by Rotary International , japan, the USA, Australia and UNICEF, is plann ing to upgrade Chinese vi rology laboratories to cope with the expanded workload. As one donor puts it: "If these improvements are not made soon , C hina could even face the possibility of having eradicated polio and not be ing able to prove it to a sceptical world." 7