During the peak enterovirus season each year, enterovirus 71 (EV71) has been found to cause widespread infection among children, leading to critical conditions or even death. A domestically developed vaccine for EV71 has entered phase III clinical trials and could hit the market as soon as before the end of 2020. The vaccine could be Taiwan’s first domestically developed pediatric vaccine. Throughout the vaccine’s development, researchers have identified VP2 as EV71’s antigenic epitope, and to ensure the quality of the vaccines, the findings have been patented in Taiwan and the U.S.

Following the first outbreak of enterovirus in 1998 that led to the death of 78 children, Director Monto Ho of the Division of Clinical Research at the National Health Research Institutes (NHRI) led a team that identified the main culprit as EV71 and urged the government to commence a program for a domestically developed human use vaccine. The Center of Disease Control’s (CDC) Chief of Vaccines Chiang Cheng-jung recalled that with a stroke of luck, the research team identified the EV71-E59 virus strain in their small lab in Kunyang, which marked the beginning of a journey to find a vaccine for EV71.

Liu Chia-Chi, an associate researcher at the NHRI’s National Institute of Infectious Diseases and Vaccinology, said that the VP2 antigenic epitope resides in the cell receptor binding domain and is relatively stable with few mutations. Therefore, an effective vaccine against EV71 could be made from the corresponding antigenic epitope in the protein sequence of VP2. In the past, VP1 was the internationally accepted antigenic epitope, however, its propensity to mutations have led to a lack of effective indicator of vaccine quality.

Liu said that the VP2 antigenic epitope has been found to be effective in inhibiting the virus from binding to the receptor and cutting off the infection pathway. The VP2 antigenic epitope can also be used to gauge the minimum dosage required for effective vaccination to bring the required protection with the least impact to vaccine recipients while bringing improve the cost-effectiveness of manufacturing.

Chief of Vaccines Chiang said that development of the EV71 vaccine has entered phase III clinical trials in two countries, with the studies expected to enroll a total of 7,200 children aged between two months and 6 years. An application for the approval of the new vaccine could be submitted and cleared for marketing before the end of 2020 at the soonest. The new vaccine would be geared for children between the age of two months and six years. However, whether the vaccine would be subsidized or paid for out of pocket remains to be discussed by the CDC.

【2019-06-26 / United Daily News】