The WHO-EPI initiative for the global eradication of poliomyelitis.

Since the development of attenuated oral polio vaccine, Dr Albert Sabin consistently maintained that the global eradication of wild poliovirus was possible, but that to achieve polio eradication in developing countries would require the mass administration of the oral vaccine. Experience in Cuba and Czechoslovakia proved the effectiveness of this technique, but it was only with its deployment in Brazil in 1980 that its role in eradicating the virus from a broad geographical area started to be realized. With the declaration in 1985 of a target of regional polio eradication, extension of this policy, allied with the development of effective surveillance of acute flaccid paralysis in children, with laboratory confirmation of diagnosis rapidly led to apparent interruption of wild poliovirus transmission throughout the Americas. The World Health Assembly in 1988 committed WHO to the global eradication of poliomyelitis. Based on experience in the Americas and building on the solid foundation established by the Expanded Programme on Immunization, WHO has defined the strategies through which the global target could be achieved. Progress is encouraging and where the advocated strategies have been fully implemented, the incidence of poliomyelitis has declined dramatically. Significant geographical areas in Western Europe, the Maghreb, the Arabian peninsula, the Pacific basin and Southern Africa, each incorporating several countries, are now thought to be free of the disease caused by wild poliovirus. The target of a world free of polio by the year 2000 can be achieved.

Studies of missed opportunities for immunization in developing and industrialized countries.

Missed opportunities for immunization are an obstacle to raising immunization coverage among children and women of childbearing age. To determine their global magnitude and reasons, studies reported up to July 1991 were reviewed. A standard measure for the prevalence of missed opportunities was calculated for each study. Seventy-nine studies were identified from 45 countries; 18 were population-based, 52 were health-service-based, and 9 were intervention trials. A median of 32% (range, 0-99%) of the children and women of childbearing age who were surveyed had missed opportunities during visits to the health services for immunization or other reasons. Missed opportunities were mainly due to failure to administer simultaneously all vaccines for which a child was eligible; false contraindications; health workers' practices, including not opening a multidose vaccine vial for a small number of persons to avoid vaccine wastage; and logistical problems. To eliminate missed opportunities for immunization, programmes should emphasize routine supervision and periodic in-service training of health workers which would ensure simultaneous immunizations, reinforce information about true contraindications, and improve health workers' practices.

PIP: The authors review studies reported up to July, 1991, on the global magnitude of and reasons for missed opportunities to immunize children and women of childbearing age. A standard measure was calculated for the prevalence of missed opportunities for each of the 79 studies identified from 45 countries; 18 were population-based, 52 were health-service-based, and 9 were intervention trials. A median of 32% over a range of 0-99% children and women of childbearing age surveyed had missed opportunities during visits to health services for immunization or other reasons. These outcomes were due mainly to the future to administer simultaneously all vaccines for which a child was eligible; false contraindications; health workers' practices; and logistical problems. To eliminate these missed opportunities, programs should emphasize routine supervision and the periodic in-service training of health workers. This approach would ensure simultaneous immunizations, reinforce information about true contraindications, and improve health workers' practices.

EPI for the 1990s. The Expanded Programme on Immunization Team.

This paper highlights the achievements, lessons learned, goals, policies, strategies and approaches for the Expanded Programme on Immunization for the 1990s. The Programme's Global Advisory Group endorsed the paper in October 1991, together with actions proposed for the 1990s. Figures showing immunization coverage and estimates of prevented and current mortality and morbidity are included.

Linkages between immunization and breastfeeding promotion programs.

Breastfeeding promotion and immunization are important interventions of child survival programs, especially in developing countries. Linkages between breastfeeding promotion programs and the Expanded Programme on Immunization (EPI) in developing countries mean that health care workers can make use of every contact with the mother and child to reinforce the educational messages of both programs. Breastfeeding does not interfere with vaccinations administered in accordance with the routine schedule recommended by the EPI Global Advisory Group for use in developing countries. Breastfeeding benefits the EPI and the EPI also benefits breastfeeding. The maximum reduction of morbidity and mortality will be achieved when all child survival interventions are applied in a balanced, complementary manner as envisaged in the concept of primary health care.

PIP: Breastfeeding promotion and immunization are important interventions of child survival programs, especially in developing countries. Linkages between breastfeeding programs and the Expanded Program on Immunization (EPI) in developing countries mean that healthcare workers can use every contact with the mother and child to reinforce educational messages conveyed by both programs. Breastfeeding does not interfere with vaccinations administered in accordance with the routine schedule recommended by the EPI Global Advisory Group for use in developing countries. Breastfeeding benefits the EPI and the reverse is true as well. The maximum reduction of morbidity and morality will be achieved when all child survival interventions are applied in a balanced, complementary manner as seen in the concept of primary healthcare.

Worldwide status of poliomyelitis in 1986, 1987 and 1988, and plans for its global eradication by the year 2000.

In 1986, a total of 28,951 cases of poliomyelitis were reported to WHO by 175 countries/areas. For 1987, 35,685 cases were reported by 168 countries/areas. Reporting is incomplete for 1988, based on data available as of December 1989. Trends in regional incidence rates for poliomyelitis over a 15-year period from 1974 to 1988 suggest a decline in the incidence of the disease, especially since 1982. However, the reported data underreport actual disease incidence. During 1986, 1987 and 1988, the Expanded Programme on Immunization (EPI) estimates that 200,000-250,000 cases of paralytic poliomyelitis occurred each year. With the current level of polio immunization coverage, it is estimated that 360,000 cases of paralytic poliomyelitis were prevented in 1988. In 1974, when the EPI was started, it was estimated that less than 5% of children in the developing world were adequately immunized against six common childhood diseases, including poliomyelitis. In 1988 (based on data available as of December 1989) 67% of children worldwide received a full course of polio vaccine before 12 months of age. The progress of the EPI has provided optimism that poliomyelitis can be eradicated. In May 1988, the Forty-first World Health Assembly committed WHO to the global eradication of poliomyelitis by the year 2000. The eradication of poliomyelitis will represent, along with the eradication of smallpox, a fitting gift from the XXth to the XXIst century. To reach this goal, action will be required in several main areas. Immunization coverage will need to be raised and sustained in every district. Vaccine quality must be assured by using vaccines which meet WHO requirements and maintaining the cold chain. Surveillance must be strengthened so that prompt, regular reporting of suspected cases leads to disease-containment measures. Additional actions include improving laboratory diagnostic capabilities, developing special training materials, increasing public awareness, supporting rehabilitation services and conducting essential research.

[Hepatitis B vaccine: a new force against pandemic diseases]. / La vacuna contra la hepatitis B: un nuevo frente contra las enfermedades pandemicas.

PIP: More than 2 billion people in the world are infected with the hepatitis B virus, of whom 280 million are chronic carriers. This virus is responsible for up to 80% of primary hepatic cancer, which is one of three main causes of cancer deaths in east and southeast Asia as well as Africa. Mainly young people are at risk of getting infected and becoming chronic carriers. 70-90% of infants who are infected at birth will become chronic carriers. The virus is transmitted via body fluids, especially blood. It can be transmitted among children and from mother to child during the perinatal period. The vaccination program against hepatitis B is an important tool for preventing its spread. Vaccines contain the viral surface antigen (HBsAG) and are produced from plasma by recombinant DNA techniques. If it is administered properly, a 95% rate of immunization against hepatitis B is achieved. Over the years, more than 40 million doses have been administered. A complete regimen of three doses produces excellent seroconversion rates. The minimum time required between doses is 4 weeks, but a longer interval is preferable between the second and third doses. Since the probability of perinatal infection is low, the first dose may be administered from the sixth week in conjunction with the first dose of diphtheria-pertussis-tetanus (DPT) vaccine. The subsequent doses should coincide with the administration of other vaccines. The hepatitis B vaccine could be administered simultaneously with measles, DPT, poliomyelitis, and BCG vaccines. Complete immunization against hepatitis B costs $2.80 for three doses--an amount that could decline in the coming years.^ieng

Linkages between immunization and breastfeeding promotion programs.

Breastfeeding promotion and immunization are important interventions of child survival programs, especially in developing countries. Linkages between breastfeeding promotion programs and the Expanded Programme on Immunization (EPI) in developing countries mean that health care workers can make use of every contact with the mother and child to reinforce the educational messages of both programs. Breastfeeding does not interfere with vaccinations administered in accordance with the routine schedule recommended by the EPI Global Advisory Group for use in developing countries. Breastfeeding benefits the EPI and the EPI also benefits breastfeeding. The maximum reduction of morbidity and mortality will be achieved when all child survival interventions are applied in a balanced, complementary manner as envisaged in the concept of primary health care.

The expanded programme on immunization: a decade of progress in India.

The Expanded Programme on Immunization (EPI) was initiated in India in 1978 with the objective to reduce morbidity and mortality from diphtheria, pertussis, tetanus, poliomyelitis and childhood tuberculosis by providing immunization services to all eligible children and pregnant women by 1990. Measles vaccine was included when the EPI was accelerated by launching the Universal Immunization Programme (UIP) in 1985-6. Approximately half of all infants now receive complete primary immunization with diphtheria, polio and tetanus (DPT), oral polio vaccine (OPV) and BCG vaccine. Forty-six per cent of pregnant women currently receive a second or booster dose of tetanus toxoid (TT). Surveillance reports from selected areas have documented impact through reduction of disease incidence. Although vaccination coverage levels are increasing, continued acceleration is needed to achieve the universal levels targeted for 1990.

Poliomyelitis surveillance and vaccine efficacy in Bombay, 1982-87.

Reported are updated data on poliomyelitis surveillance in Bombay for the period 1982-87 and estimates of the efficacy of oral poliovaccine (OPV) calculated by the case exposure method, using two approaches. The first, a screening technique that used only data on the reported number of doses of vaccine administered and the immunization status of all poliomyelitis cases, appeared to underestimate the true vaccine efficacy. In the more rigorous second technique, which used data for children of the same age group, geographical areas, and study year, obtained from immunization coverage surveys, and information on the immunization status of poliomyelitis cases, the results indicate that the OPV vaccine efficacy for fully immunized children aged 12-23 months exceeded 90%. These findings show that the estimated efficacy of OPV is high in Bombay and that, in general, vaccine efficacy should be re-estimated using more rigorous techniques if preliminary screening estimates indicate a lower than expected efficacy. In Bombay, poliomyelitis therefore results primarily from a failure to fully vaccinate all eligible children rather than as a result of vaccine failure. Furthermore, the age distribution of cases suggests that the strategy of focusing immunization activities on children aged under 1 year is epidemiologically correct.

Poliomyelitis surveillance and vaccine efficacy in Bombay, 1982-87

Reported are updated data on poliomyelitis surveillance in Bombay for the period 1982-87 and estimates of the efficacy of oral poliovaccine (OPV) calculated by the case exposure method, using two approaches. The first, a screening technique that used only data on the reported number of doses of vaccine administered and the immunization status of all poliomyelitis cases, appeared to underestimate the true vaccine efficacy. In the more rigorous second technique, which used data for children of the same age group, geographical areas, and study year, obtained from immunization coverage surveys, and information on the immunization status of poliomyelitis cases, the results indicate that the OPV vaccine efficacy for fully immunized children aged 12-23 months exceeded 90 percent

These findings show that the estimated efficacy of OPV is high in Bombay and that, in general, vaccine efficacy should be re-estimated using more rigorous techniques if preliminary secreening estimates indicate a lower than expected efficacy. In Bombay, poliomyelitis therefore results primarily from a failure to fully vaccinate all eligible children rather than as a result of vaccine failure. Furthermore, the age distribution of cases suggests that the strategy of focusing immunization activities on children aged under 1 year is epidemiologically correct(AU)