New cholera vaccines.

Development of improved cholera vaccines has progressed rapidly in recent years. An oral killed vaccine, designed to evoke antibacterial as well as antitoxic intestinal immunity, has proved to be completely safe and to protect against cholera for at least 3 years. This vaccine also confers substantial though more short-lasting immunity against diarrhoea caused by enterotoxigenic Escherichia coli. Significant progress has also been made towards developing a live attenuated cholera vaccine using recombinant DNA techniques. The advent of effective oral cholera vaccines gives hope for improved control of cholera in the Third World.