| Abstract: | Focus of this discussion is on some of the problems enountered by national immunization programs and on the technology that is available now or that will be in the near future to help solve these problems. 4 basic aspects of immunization services are examined: the safety, effectiveness, and stability of vaccines; the cold chain, i.e., the transportation, storage, and handling of heat-sensitives vaccines from manufacturer to health worker in the field; vaccination equipment and sterilization for correct administration of immunization; and program management--schedules, records, training, resource allocation. The section devoted to vaccines focuses on immunization against 6 of (diphtheria, whooping cough, tetanus, measles, polio, and tuberculosis) against 6 of the major killers of children in developing countries: BCG, DPT (diphtheria-pertussis-tetanus), measles and poli vaccines, and tetanus toxiod. The bacillus of Calmette and Guerline (BCG) is considered a very safe vaccine. Questions about the effectiveness of BCG in preventing tuberculosis have been raised throughout its 60-year history. Different studies have produced conflicting results, some showing BCG to be highly effective and others showing no positive effect. Diphtheria toxioid, a very safe and relatively stable vaccine, is very effective in protecting against the development of diphtheria. Live attenuated measles virus vaccine is a safe, highly effective vaccine, but it requires careful handling and storage to prevent damage due to excessive heat or light exposure. The vaccine used for pertussis (whooping cough) is a saline suspension of killed Bordetella pertussis bacteria. The vaccine usually is administered as part of the triple DPT vaccine. Concerns about its safety have led to greatly reduced levels of use in some European countries in recent years. Its effectiveness also has been questioned. 2 types of polio vaccine are available: a live, attenuated vaccine given orally (Sabin) and a killed or inactivated vaccine injected intramuscularly (Salk). Both vaccines are trivalent, i.e., they contain all 3 major strains of polio virus. Both types of vaccine are quite safe. Effectiveness of the vaccines seems to vary in different places. Tetanus toxoid is safe and relatively stable. The 3 doses of DPT given to infants provide long-lasting protection against tetanus. To combine the components of vaccine and equipment into an effective immunizaton service, a program manager must consider several issues: program goals and the development of an appropriate and feasible immunization schedule; systems for keeping records and for training health and cold chain personnel; analysis of the costs of each option; and the development of a method of evaluation. |
