Measles in the cities

32 World Health • 49th Year, No. 1, January-February 1996 Measles in the cities John elements Measles immunization is one of the most cost-effective public health tools; it makes good sense to concentrate measles control in the cities, where case fatality rates are highest and the disease causes greatest damage. Bringing immunization to underserved areas in the cities is a vital- and potentially difficult - part of the Expanded Programme on Immunization (EPI). Special activities are called for to achieve high vaccine coverage and target specific diseases for control. Focusing on urban measles control helps programme managers to in- crease coverage for the other EPI diseases at the same time. Using World Health Day 1996 to promote measles immunization among the urban poor is an opportu- nity that must not be missed. Even though global coverage of 78% for measles vaccine has been achieved, over a million children still die from measles each year and another 43 million contract the disease, many of whom will suffer severe complica- tions. Measles immunization has been called one of the most cost- effective public health tools ever invented, so to concentrate measles control on the cities- where case A child being immunized against measles during a mass campaign. Measles immunization is one of the mast cost-effective public health measures. fatality rates are highest and the disease does the most damage - makes good sense. The additional resources required are well justified in both economic and humanitarian terms. Routine immunization services may not be enough by themselves to control the EPI target diseases. Floods and other natural disasters sometimes hamper the work, urban slums are often underserved, and their inhabitants tend not to use existing services. High risk Measles, poliomyelitis and neonatal tetanus cases do not occur at random throughout the population, but can be seen to cluster in certain geo- graphical areas (high-risk areas) and in certain population groups (high- risk groups). For measles, high-risk areas are those with a high popula- tion density, high mobility, and low immunization coverage. Most high-risk groups are found in such areas, where children may also be malnourished and vitamin A-deficient. They include mobile populations, ethnic minorities and refugees, all of whom tend to gravi- tate towards the poor areas of cities. Because these groups are often hard to reach with immunization services, countries may have to adopt new strategies to ensure that the vaccine reaches those not at present served by fixed centres; they also need to target an expanded age range of at least 9 to 36 months. The strategy of using urban mass campaigns to immunize high-risk groups has been endorsed by WHO, UNICEF and the Children's Vaccine Initiative. If it is to succeed, measles control in urban areas will require enthusiasm from donors and national programmes. Efforts to raise measles vaccine coverage needs to be accelerated through national or subnational immunization days to World Health • 49th Year, No. 1, January-february 1996 reduce measles in these areas. Measles campaigns should be imple- mented rapidly in every high-risk situation as an additional strategy to control this disease. Five aspects of the epidemiology of measles are particularly important for control activities: • the virus circulates easily in densely packed communities where children are under-immu- nized; • the phenomenon of "seeding" occurs, whereby urban measles is seeded or exported to nearby villages and towns which might otherwise be free of the disease (or at any rate have a much lower incidence); • studies in a number of cities show that measles continues to circulate in the urban environ- ment despite reasonable immu- nization coverage, so even if routine coverage exceeds 80%, the disease may not be elimi- nated from the densely populated areas through routine immuniza- tion services; • measles case fatality rates are highest in very young children who contract the disease, and cases in cities tend to occur at Measles still hits many millions of children throughout the world. Using World Health Day 1996 to promote immunization among the urban poor is on opportunity that must not be missed. younger ages; • measles in the cities frequently loses its tendency to fluctuate with the seasons, and continues like a smouldering fire which never goes out. Multi-disease campaigns Health authorities will need to de- cide whether measles control is a top priority for them, and whether they can afford to provide other vaccines at the same time. Many urban high- risk districts for measles will also be at high risk for neonatal tetanus and polio. It may be possible to run multi-disease campaigns simultane- ously for measles and oral polio vaccines as well as tetanus toxoid for women of childbearing age. Vitamin A should also be considered as a low-cost effective intervention at the same time. The cost of a campaign in the urban slums will not be great. Partners such as UNICEF and vari- ous nongovemmental organizations will find it an attractive venture because it reaches top priority groups and will have a big impact on the target diseases. Experience in the Americas suggests that the full cost of a measles mass campaign ranges from US$ 0.50 to 0.75 per child; if administered during a polio mass campaign, the cost additional to that of polio is about $0.30 per child. Funds will be needed to purchase vaccine, syringes and needles. WHO and UNICEF recom- mend the autodestruct syringe for campaigns such as this. Areas and populations which in the past are likely to have resisted invitations to come forward for immunization need to be specifically targeted and new ways must be sought to reach them or attract them to fixed centres. World Health Day 1996 offers a particularly good opportunity for introducing such new approaches. Bangladesh has set a good exam- ple with its 1995 immunization campaign for tetanus toxoid and 33 measles vaccine. All high-risk districts for measles are in poor urban areas. Today, overall coverage for all antigens has increased to around 75% but is lower in high-risk areas. Manila in the Philippines and Lagos in Nigeria are also under- taking lively urban immunization programmes. • Or John Clements is Medical Officer with the Expanded Progrommme on Immunization, Global Programme for Voccines and Immunization, World Health Organization, 121 1 Geneva 27, Switzerland Collecting cowdung to be used as fuel. Unfortunately this practice spreads tetanus spores in the environment, making protection with tetanus toxoid for all women of childbearing age all the more important.