Vaccine technologies: view to the future.

The development of vaccines to prevent infectious diseases has been one of the most important contributions of biomedical science. Recent advances in the basic sciences are now fueling the development of a new generation of vaccines that will be based on rational design approaches. Two factors are making this possible: an improved understanding of the microbial factors required for virulence and the nature of the immune response to infection. The status of new vaccine technologies is summarized here.

Vaccines. Overview.

PIP: This paper examines the role of epidemiology in reducing the health burden of infectious diseases through vaccination. Epidemiology has played a part in all aspects of immunization by: 1) defining the health burden of infectious diseases meriting prevention; 2) determining populations at risk for disease and disease complications; 3) evaluating modes of transmission and the groups critical to sustaining transmission of infectious agents; 4) estimating the effectiveness of a given vaccine and vaccine policy; 5) determining reasons for failure to control disease, and suggesting solutions; 6) assessing the safety of vaccines, and reevaluating risk-benefit analyses; and 7) determining the most effective strategies for vaccine delivery. The controlled studies, observational studies, and disease surveillance have produced advances in the control of vaccine-preventable diseases. The most effective use of vaccines would depend on the introduction of vaccines in areas where disease epidemiology finds it beneficial to health.^ieng

The promise of new technologies.

Efforts to provide the benefits of immunization to the world's children have reached an important crossroad. While remarkable progress has been achieved in successfully administering six important childhood vaccines (diphtheria, tetanus, polio, pertussis, measles, and tuberculosis), the benefits of new vaccines, such as hepatitis B and Haemophilus influenzae type B glycoconjugate vaccines, have not been realized except in the most developed countries. The three reasons often cited to explain this problem include poor access to immunization services, the evolution of complex primary immunization schedules, and the additional expense associated with new vaccines, potentially depleting scarce resources. The establishment of the Children's Vaccine Initiative is an organized effort to improve immunization by both technological and organizational innovation. Simplification of the vaccination process can be achieved by developing new combination vaccines or reducing the number of immunizations with vaccines that stimulate protective immune responses. Improvements in the organization of efforts to immunize children will also enhance the prospects of protecting the world's children from infectious diseases. To achieve the goals articulated in the Declaration of New York, the issues of transition from the old to the new vaccines must be addressed. Research on vaccines and technological innovation at all levels will be required to achieve these goals.

A model for estimating the impact of changes in children's vaccines.

OBJECTIVES: To assist in strategic planning for the improvement of vaccines and vaccine programs, an economic model was developed and tested that estimates the potential impact of vaccine innovations on health outcomes and costs associated with vaccination and illness. METHODS: A multistep, iterative process of data extraction/integration was used to develop the model and the scenarios. Parameter replication, sensitivity analysis, and expert review were used to validate the model. RESULTS: The greatest impact on the improvement of health is expected to result from the production of less reactogenic vaccines that require fewer inoculations for immunity. The greatest economic impact is predicted from improvements that decrease the number of inoculations required. CONCLUSIONS: Scenario analysis may be useful for integrating health outcomes and economic data into decision making. For childhood infections, this analysis indicates that large cost savings can be achieved in the future if we can improve vaccine efficacy so that the number of required inoculations is reduced. Such an improvement represents a large potential "payback" for the United States and might benefit other countries.