Development of the hepatitis E vaccine: from bench to field.

Along with the improvement of diagnostic techniques, hepatitis E has attracted increasing awareness in recent years. Hepatitis E virus infection leads to high mortality in pregnant women and patients with underlying liver disease. Several hepatitis E vaccine candidates have been designed and have proved their efficacy in animal models; two candidates have successfully undergone clinical trials. Having proved safe and effective in a large phase Ill trials, an Escherichia coli expressed particulate protein, HEV 239, has been registered in China and is now available for use in China.