Enimmune Corp. (TWSE: 6564), a subsidiary of Adimmune Corporation, today announced the unblinding results of its phase III clinical trial for EnVAX-A71, Enimmune’s enterovirus 71 (EV71) vaccine. The trial demonstrated an impressive vaccine efficacy of 99.21%, establishing EnVAX-A71 as the most effective EV71 vaccine currently available worldwide. 

Enterovirus is prevalent in Asia. Children under 5 years of age infected with EV71 are prone to severe complications. In 1998, Taiwan experienced its first outbreak of severe hand, foot and mouth disease and herpangina, which infected approximately 1.4 million children and resulted in 405 cases of severe complications and 78 deaths. EV71 is a leading cause of serious neurological complications.  

The phase III clinical trial of EnVAX-A71 was a multinational and multicenter study that enrolled a total of 3,993 subjects. In Taiwan, 1,266 subjects participated among seven medical centers: China Medical University Hospital, National Taiwan University Hospital and its Hsinchu Branch, Taipei Veterans General Hospital, Linkou Chang Gung Memorial Hospital, Taichung Veterans General Hospital, and Changhua Christian Hospital. The international phase III subject recruitment, conducted in collaboration with the Pasteur Institute of Vietnam, started in 2022. A total of 2,727 subjects were enrolled in two pilot hospitals located in Ben Tre Province and Vinh Long Province in Vietnam. 

During the trial period, a total of 71 confirmed EV71 cases were tracked, two cases in Taiwan and 69 cases in Vietnam. Among them, one case was from the vaccine group and 70 were from the placebo control group. Using the formulas from the Guidelines for Clinical R&D Strategies of Enterovirus Vaccine and the clinical trial protocol, the vaccine efficacy was calculated to be 99.21%. Poisson regression analysis showed a 95% confidence interval of 94.31% to 99.89%, with a p-value of less than 0.001, demonstrating statistical significance. 

“We extend our deepest gratitude to the subjects and their parents who participated in the phase III clinic trial, contributing to this successful unblinding. The dedication of these families allowed us to validate EnVAX-A71’s effectiveness in the real world,” said Vic Chang, President of Enimmune Corp.. “During Vietnam’s EV71 epidemic in 2023, the rising number of positive cases enabled us to demonstrate that EnVAX-A71 is not only safe and protective but also competitive on the international stage.”  

EnVAX-A71 received the marketing authorization from Taiwan’s Food and Drug Administration in 2023. By selecting the B4 subgenotype strain, which is prevalent in Taiwan, and utilizing Adimmune’s cell culture bioreactor and high-yield manufacturing process, the production capacity for EnVAX-A71 is expected to significantly increase starting from 2025. Additionally, a distribution contract has been signed with VABIOTECH, Vietnam’s largest state-owned vaccine company, to expand into the Southeast Asian market. The marketing authorization application will soon be submitted in Vietnam. The next steps include targeting the neonatal market in Southeast Asian countries and the market in Mainland China. 

Since the launch of EnVAX-A71, Enimmune has strengthened its presence in the pediatric vaccine and testing market. The company is planning to file an application with the Taiwan Stock Exchange in mid-July for listing on the Taiwan Innovation Board.