Human immunization in developing countries: practical and theoretical problems and prospects

While measles, pertussis and tetanus were responsible during the early 1990s for nearly two million deaths in developing countries, no deaths were attributable to them in industrialized countries. More than 96% of global deaths by communicable diseases were also from developing countries. Respiratory infections ranked first in communicable morbidity at all ages. Even though vaccines of bacterial or viral origin or a prophylactic for passive immunization are produced in 24, 16 and 15 developing countries, respectively, none of the developing countries manufactures a plasma-derived prophylactic or biological response modifier. Nearly every country relies on import of one or more vaccines. The suboptimal performance of otherwise meritorious products has been due to faulty vaccine administration practices. Expanding populations, poverty and lack of education, cold-chain defects, and inadequate facilities for transport of vaccines to target populations in remote areas have been responsible for the poor performance of vaccines in the community. Mounting foreign debts and budgetary strains resulting from the care and prevention of AIDS/HIV have considerably strained national and international efforts to offer routine vaccinations in childhood and pregnancy. This dismal situation could be tackled through research to obtain environmentally stable products for prophylactic use and monoclonal antibody formulations for passive immunization, and through international financial and technical support. All countries should exercise some technical control of the quality of imported and indigenous vaccines during their use for curative or prophylactic purposes. The involvement of private clinicians in immunizations would strengthen national efforts for control of communicable diseases including AIDS, but this is not enough if the local factors cited above are not improved.This paper opens by briefly tracing the development of vaccines from Edward Jenner's work in 1796 to the present. The proportion of deaths from communicable diseases in developed and developing countries is discussed, and it is noted that, in 1990, communicable diseases killed 575,000 people in industrialized countries and 16 million people in developing countries. In developed countries, there were no deaths from measles, malaria, tetanus, or pertussis, and only seven from diarrheal disease as compared to 1,006,000, 926,000, 505,000, 321,000, and 2,866,000, respectively, in developing countries. By the end of the century, AIDS will overshadow the communicable disease profile. Annual mortality figures from bites by rabid animals, snakes, insects, etc. are also grossly underreported. A look at the common biologicals used in developing countries shows that at least eight bacterial and eight viral vaccines are in common use globally. The origin and indications for each vaccine are tabulated. Data on anti-serum vaccines, plasma-derived preparations, and biological response modifiers (available in industrialized countries) are similarly tabulated. Consideration of the industrial production of immunogens in developing countries reveals that most production relies on outdated technology. Vaccines exhibit suboptimal performance in these settings either due to factors relating to individual vaccines or to community circumstances. Individual vaccines which exhibit inadequate potency in adverse circumstances include liquid vaccines and lyophilized vaccines and prophylactics. This situation is exacerbated by unsatisfactory vaccine administration practices, malnutrition, and cases of immunosuppression. Suboptimal performance at the community level is due to procurement procedure, the cost of vaccines, poverty, population growth, failures in the cold chain, lack of trained personnel, religion and gender bias, and political factors, such as war. A suitable remedial action plan requires integrated action at the international, national, and community levels. Such an effort would be aided by improved mortality data collection techniques and by multidisciplinary research to update indigenous manufacturing technology.