Whither immunization against viral infections?

Economic and social considerations with respect to the infectious diseases demand increased application of preventive measures. Vaccines provide high benefit at low cost and low risk. Past vaccines have emphasized use of live attenuated, or killed whole, or fractionated organisms. Future vaccines will involve recombinant and synthetic antigens, with emphasis on control of many different infections with single polyvalent vaccines directed against individual epitopes rather than complex antigens. Heightened interest in preventive medicine is evident among physicians, aided by the activities of the World Health Organization and governments, and individual academic and public health initiatives. An overview of the past, present, and future with respect to technological possibilities and other practical considerations for vaccines is presented.