A Phase 1, Double-Blinded, Placebo-Controlled Clinical Trial to Evaluate the Safety and Immunogenicity of HEV-239 (Hecolin) Vaccine in Healthy US Adults

Background: Establishing the safety and immunogenicity of a hepatitis E virus vaccine in multiple populations could facilitate broader access and prevent maternal and infant mortality.

Methods: We conducted a phase 1, randomized, double-blinded, placebo-controlled (4:1 vaccine to placebo) trial of 30 µg HEV-239 (Hecolin, Xiamen Innovax Biotech Company Limited, China) administered intramuscularly in healthy US adults aged 18-45 years. Participants were vaccinated on days 1, 29, and 180. Participants reported solicited local and systemic reactions for 7 days following vaccination and were followed through 12 months after enrollment for safety and immunogenicity (IgG, IgM).

Results: Solicited local and systemic reactions between treatment and placebo group were similar and overall mild. No participants experienced serious adverse events related to HEV-239. All participants receiving HEV-239 seroconverted at 1 month following the first dose and remained seropositive throughout the study. HEV-239 elicited a robust hepatitis E IgG response that peaked 1 month following the second dose (geometric mean concentration [GMC], 6.16; 95% confidence interval [CI], 4.40-8.63), was boosted with the third dose (GMC, 11.50; 95% CI, 7.90-16.75) and persisted through 6 months.

Conclusions: HEV-239 is safe and elicits a durable immune response through at least 6 months after the third dose in healthy US adults.

Clinical Trials Registration: NCT03827395.