Modern approaches to vaccine development with special reference to the needs of developing countries.

Vaccination has proved to be one of the most effective public health measures to control infectious diseases. The eradication of smallpox by world-wide vaccination represents one of mankind's greatest achievements. Despite the availability of vaccines to control many diseases, they are generally under-used in many developing and some developed countries. However, there are many diseases for which current vaccines are inadequate or vaccines cannot be prepared using conventional approaches. This article describes the new approaches which are now available and are being used extensively to develop new vaccines against viral, bacterial and parasitic diseases. Success has already been achieved in a few cases and the prospect for others is encouraging. In addition, progress is being made to develop vaccines to control human fertility as this development is seen to complement the control of infectious diseases.