A number of new vaccines with major potential for controlling infectious diseases have just been licensed or are at advanced stages of development. Among the illnesses targeted are rotavirus diarrhoea, pneumococcal disease, and cervical cancer (as caused by human papillomavirus), which together kill more than a million people each year, most of them in developing countries. In addition to these efforts against diseases of global importance, progress is being made on a vaccine for the regional menace posed by meningococcal meningitis serogroup A, which causes frequent epidemics and high rates of death and disability in African countries south of the Sahara.
These advanced candidate vaccines are the focus of the information provided below. However, it should be noted that continuing, intensive efforts are under way to develop effective vaccines for AIDS, malaria, tuberculosis, dengue, leishmaniasis, and enteric diseases, among others and to adapt new technologies to improved formulation and delivery.
Vaccine development proceeds through discovery, process engineering, toxicology and animal studies to human Phase I, II, and III trials. The process can take more than 10 years, depending on the disease. The human trials focus initially on safety, involving small groups of people (I); then progress to moderate-sized "target" populations (persons close to the age and other characteristics for whom the vaccine is intended) to determine both safety and the stimulation of immune response (II); and finally to large target populations to establish whether a vaccine actually prevents a disease as intended (efficacy) (III).
http://www.who.int/mediacentre/factsheets/fs289/en/index.html
