Polio eradication: part and parcel of EPI

I I part and 111rce1 of EPI At the World Health Assembly last May, WHO unveiled its plan to eradicate poliomyelitis by the year 2000. In an interview given to our colleague Ruth Landy, Or Ralph Henderson, head of the WHO Expanded Programme on Immunization (EPI), explained that, without the system established since 197 4 under this programme, we could never have dreamt of polio eradication. Dr Ralph Henderson: In the last decade or so we have transformed public health in many developing countries by providing, for the first time, immunization against six "killer" diseases of childhood: diphtheria, per- tussis, tetanus, measles, tuberculosis, and poliomyelitis. In 197 4, when the Expanded Programme on Immuni- zation (EPI) started, less than five per cent of children in developing coun- tries were benefitting from the vaccines that are in such widespread use in industrialised countries. Today this coverage is some 60 per cent, and we are shooting to reach 80 per cent or more of all children in the world - and that means all children in the developing countries, too - by the end of 1990. World Health: Why has the world community decided it is ready to try to achieve polio eradication in particular? RH: We have got some excellent vaccines, and we have seen a virtual disappearance not only of the disease 6 but of the wild virus in many of the industrialised countries. However, polio is going to be a much more difficult disease to eradicate than smallpox was - Or D. A. Henderson, who led the worldwide successful effort against smallpox in WHO in the 1970s, explains why in this issue - but we think we can do it, provided we start now. Another reason for choosing polio is that it is a disease that is not only feared, but it is a disease you love to hate. It strikes mainly young child- ren, most of them in their first five years of life, some even in their first year. And it does not kill very much, but it does cripple, and the crippled child in developing countries will often be seen crawling along the sidewalk, begging, selling pencils. Poor countries cannot always afford rehabilitation services for those children, who live lives which may be shortened because of their paralysis, and are really in a very distressing state. So we have a lot of enthusiasm from people who would like to see us get rid of it. WH: How many children are affected at this point, and when should a child be vaccinated to protect it against polio? RH: Over 40 million children are infected by the virus, most of whom have not got paralysis, but unfortu- nately 200,000 children are paralysed each year by the disease. When should children be immu- nized? We would like to start polio immunization in the industrialised countries with the first dose of OPT, the vaccine against diphtheria, per- tussis and tetanus. Polio and OPT, given together, work very well. In countries where polio still exists, we would like to give the first dose of the oral polio vaccine at birth, or as soon as possible afterwards. It does not mean that we necessarily have to go out and find each child at the time of birth, but it does mean that a child at any age, who is seen by a health worker, is never too young to be given W ORLD HEA LTH , December 1989 EPI is combating six "killer" diseases. But polio is the one most people love to hate, because it cripples children - especially in countries which can rarely afford rehabilitation services. the polio vaccine. Three doses should be given, spaced at about a month apart. Health workers should induce parents to seek immunization services early for their child, so that the disease does not strike before the immuni- zation can be given. WH: Are some parts of the world making faster progress than others? RH: The Region of the Americas - in part because it has relatively well- developed health services compared to some other regions - took the lead in this. They are probably going to make it by the end of 1990. It is odd because Europe, of course, is the Region that is most advanced with its health services, and you would think, my goodness, isn't the Region of Europe already free WORLD HEALTH. December 1989 of polio? And it turns out, no, it isn't. Parts of the Soviet Union, for instance, have all the problems of a developing country, and there are indeed scattered cases of polio in some remote parts of that country. Many other countries in Europe are probably polio-free, but we cannot document it. They haven't done the rigorous testing of virus specimens from each suspected case, and an interesting part of our programme now is to encourage them to document each case they have got. I think we are going to see Europe free of polio by at least 1995. So the Americas and Europe are two leaders. A country like China, with one-fifth of the whole global population, is an extraordinary case. It has just done an incredibly successful immunization pro- gramme. It reached a level of 96 per cent coverage with a third dose of polio just this last year, and has confined the polio-infected areas to a few remote areas. So, China is going WHO/ L Matlowski to add its voice to the countries who clamour for polio eradication in the rest of the world. WH: Dr Henderson, what are the greatest challenges for the EPI that this polio eradication effort brings? RH: Sustained ability of the pro- gramme to maintain immunization levels is a major challenge. I see the polio initiative as being a major force in ensuring that we will sustain the enthusiasm and the focus of the programme. It is difficult for us to be sure that communities, mothers, teachers, com- munity leaders are sensitised to the priority of immunization and, again, we hope we can do that through the polio initiative. Another challenge is posed by the children who unfortunately are crippled by polio, those that we have not been able to reach quickly enough with our vaccines. So, we are now just beginning a community-based rehabili- tation effort. A mother who has a child who has been recently infected can 7 learn very simple exercises that she can go through with her child each day, to prevent that . child from developing malformations. An additional advan- tage of this rehabilitation effort will bring us into intimate contact with families and communities, and add a very important dimension to the pro- gramme. Apart from those· social kinds of issues, there are some technical ones too. Although they are good, the 8 The schedule for polio protection calls for a first dose as soon as possible after birth (above), then two more doses about one month apart. A child in Myanmar (Burma) being immunized against tuberculosis (right), one of the target diseases of the EPI. Unhealthy water (far right) can cany the polio- virus; detecting this virus in the environ- ment will be one of the challenges of the eradication eHorts in the next decade. vaccines are not perfect. The oral vaccine is not as heat stable as we would like, and does not always work as perfectly as we would like. We would like to do some research on a better vaccine. We might be exper- imenting with using the oral, or Sabin, vaccine, together with the inactivated, or Salk, vaccine. There has often been a real war between the people who are using the oral vaccine and the inacti- vated vaccine, each one thinking theirs was the best. It turns out that both are very good, and we will be looking at ways of combining the two to get the best advantages of both. How can we be sure? Another technical problem is, how are we going to tell when the virus is eradicated? We have to develop very good search techniques to detect the virus in the environment and to test W ORLD HEALTH, December 1989 Polio eradication: part and parcel of EPI our search capability in the next decade. WH: How will you be able to tell the world that the polio virus has indeed been eradicated from the face of the earth? RH: Our expectation is that we will follow much the same pattern that we did with smallpox. We will be searching as hard as we can and there will come a time when we will have not found a single virus. Then we will start a period of waiting, looking, trying to be sure that we were not just mistaken, that there was not some odd pocket of virus around. I presume that we may want to offer incentives so that there is real active search for the virus. Then after a period of two to three years, if we have not found anything indicating that the virus was there, we would finally say: OK we are convinced there isn't any more disease, there isn't any more virus, the disease has been eradicated. WH: Is this your greatest challenge so far? RH: Yes and no. The whole challenge was creating a programme like the Expanded Programme on Immuni- zation, a system that works so well. Without this system we never could have dreamt of polio eradication. It would obviously be a tremendous triumph to eradicate polio. But I ·am also very proud to have a system that will not only deliver polio vaccine, but if we get a malaria vaccine, if we get an AIDS vaccine, if we ever have other vaccines that are very important, we can deliver all of those through the programme. We can perhaps look for- ward in the next century to measles eradication, so I feel as loyal to the whole system and as proud of it as I do about its specific accomplishments. • 9