Immunogenicity and safety of a two-dose regimen with hepatitis E virus vaccine in healthy adults in rural Bangladesh: A randomized, double-blind, controlled, phase 2/pilot trial

BACKGROUND

Hepatitis E virus (HEV) is a major cause of acute viral hepatitis worldwide and it contributes to considerable maternal and neonatal mortality and morbidity in many low-income countries like Bangladesh. A three-dose regimen of a vaccine against HEV (HEV 239) has shown promising results in China. The effects and safety of this vaccine in other populations and with different dosing regimens remains uncertain.

OBJECTIVES

Investigate the immune response and safety of a two-dose regimen with the HEV 239 vaccine among healthy adults. Examine the feasibility of conducting a larger HEV 239 vaccine trial in rural Bangladesh.

METHODS

One-hundred healthy men and non-pregnant women 16-39 years old were randomized in a 1:1 ratio to receive two doses of either the study (HEV) or control (Hepatitis B virus, HBV) vaccine (at 0, 1 month). Blood samples were collected at day 0, day 60 and 2 years after vaccination. The primary endpoints were the proportion and severity of adverse events up to 2 months after dose one and the longitudinal shift in anti-HEV IgG levels from day 0 to day 60 and 2 years after vaccination.

RESULTS

Adverse events to HEV 239 were comparable to the control vaccine, mild in severity and resolved within one to nine days. All participants in the study group seroconverted and achieved high levels of HEV IgG antibodies that remained positive for two years in all but one. A T-cell response was detected one month after HEV 239 vaccination.

CONCLUSION

Our results show that two doses of the HEV 239 vaccine produces broad and likely functional immune responses against HEV that remain for at least two years. The safety profile was acceptable and a phase four study of HEV 239 in rural Bangladesh is feasible.

CLINICALTRIALS

gov Identifier: NCT02759991.

Targeted hepatitis E vaccination for women of childbearing age is cost-effective in China

BACKGROUND

Hepatitis E virus (HEV) infection is hyper-endemic in China, it is characterized with a high morbidity of fulminant hepatitis and mortality in pregnant women. The first hepatitis E vaccine, HEV 239, was licensed in China in 2011 which provides an effective preventive measure.

OBJECTIVE

To evaluate the cost-effectiveness of vaccination with HEV 239 in women of childbearing age in China and whether HEV antibody screening should be considered before vaccination.

METHODS

A decision tree-Markov model was constructed to simulate HEV infection in a closed female cohort with an average first-marriage age of 25 years and evaluate health and economic outcomes of two potential vaccination strategies, direct vaccination and combined screening and vaccination, from a societal perspective. An incremental cost-effectiveness ratio (ICER, additional costs per disability-adjusted life-year (DALY) averted) was calculated for each vaccination strategy versus no vaccination and between two vaccination strategies. Univariate and probabilistic sensitivity analyses were conducted to assess the robustness of the model findings.

RESULTS

ICERs of direct vaccination and combined screening and vaccination versus no vaccination were $4040 and $3114 per DALY averted, respectively, much lower than 1-time Chinese per-capita GDP ($8127). Direct vaccination would need additional $45,455 for each DALY averted compared with combined screening and vaccination, far more than the 3-time per-capita GDP. Probabilistic sensitivity analyses confirmed our findings that two vaccination strategies would be cost-effective if the willingness-to-pay reached the 1-time per-capita GDP, and that combined screening and vaccination would be more cost-effective than direct vaccination strategy.

CONCLUSION

Vaccinating women of childbearing age with HEV 239 would cost less than the 1-time per-capita GDP for each DALY averted in China, and the vaccination with a prior screening would be the optimal option.

The development of a recombinant hepatitis E vaccine HEV 239

Hepatitis E virus (HEV) infection is one of the main causes of acute hepatitis worldwide. A recombinant hepatitis E vaccine, HEV 239, has been licensed in China for immunizing adults of 16 y old and above. The vaccine antigen contains pORF2 aa 368 - 606 of the HEV genotype 1 expressed in E. coli. The quality of the vaccine is controlled through a combination of biophysical, biochemical and immunochemical methods. The vaccine is well tolerated in adults. The efficacy of the HEV 239 vaccine against symptomatic and asymptomatic infection had been proven to be high during a Phase III clinical trial and long-term follow up. The safety and efficacy of HEV 239 vaccine in certain high-risk populations remains to be further investigated.