Current Development and Use of Japanese Encephalitis Vaccine

Yu-Ju Chen, Feng-Kuang Hsu, Li-Ching Hsu

2013 Vol.29 NO.12

Correspondence Author： Li-Ching Hsu

Abstract：

       Although the number of JE cases has largely decreased since Taiwan started to fully implement JE vaccination program for young children in 1968, the people infected with JE virus has changed from young children population to young and mid-age adults. Since the population included in national vaccine policy currently is limited only to young children, the adults previously vaccinated with inactivated mouse brain-derived vaccine may have lost their protection levels against JE virus because the degradation of protective antibody and lack of opportunity for natural infection may lead to decrease of neutralizing antibody titers against JE virus. Although progress made in health care delivery has declined case fatality rate of JE, a patient may have been cured but continually suffer from severe and long-term mental and neurological sequels. In recent years, the cases infected with JE virus has shifted to young and mid-age population in Taiwan. Since JE has a bad prognosis, the acquisition of JE will have a big impact on patient himself, patient’s family, and society, and become a huge burden on medical cost. Therefore, how to minimize the number of JE cases is one of the most important public health issues right now. A couple of new generation JE vaccines, including inactivated JE vaccine IC51 (IXIARO®/JESPECT®) and recombinant live attenuated JE vaccine ChimeriVaxTM-JE (IMOJEV®), have been licensed for routine use by countries in Europe, America, and Asia, and have been proved to have a good immune response in vaccinated adults, except having the advantages of that only small number of doses is required and having high safety record. Of the two new generation JE vaccines, IC51 could be given in two doses to adults who never received other JE vaccines or be given as a booster shot to adults who have been vaccinated three or more doses of inactivated mouse brain-derived vaccine, and ChimeriVaxTM-JE given in one dose could provide protection that lasts as long as ten years, based on statistical prediction. Therefore, to effectively minimize the number of cases infected with JE virus among adults in Taiwan, the use of new generation JE vaccine would be a practical way. However, the safety profile and economic benefits of the new vaccine should be evaluated more carefully, to provide as a reference for policy making decisions.