Development of a Vaccination Against Hepatitis E Virus
Development of a Vaccination Against Hepatitis E Virus
Further research is needed to determine the titre of antibodies required for protection, the duration of protection afforded by the vaccine, the need for vaccine booster, and whether the vaccine is effective, not only against overt clinical illness, but also against all HEV infections.
Mitigating clinical infection and symptomatic disease, and decreasing the development of liver failure may be advantageous, even in the absence of infection prevention. Moreover, studies are needed to determine whether the vaccine would be useful for post-exposure prophylaxis, such as in cases of HEV outbreaks. Additionally, despite the serologic cross-reactivity, the efficacy of the vaccine has not been studied in regions of the world with HEV genotype 3, which has emerged as the predominant HEV strain in Europe and North America.
Additional data is needed regarding the safety and efficacy of this vaccine in individuals at extremes of age (younger than 2 years and older than 65 years), in pregnant women, and patients with chronic liver disease, as well as in immunosuppressed patients.
Preliminary evidence showed safety of the Hecolin® vaccine in pregnant women; 37 women who received 1, 2 or 3 doses of the vaccine turned out to be pregnant at time of administration. The vaccine was well-tolerated, and the delivered babies were healthy. These findings should be confirmed in larger studies.
Cost-effectiveness (C/E) of the vaccine should also be explored. C/E of an intervention is defined as the additional cost required per additional unit of health benefit produced as compared with the next-most effective alternative; this must be distinguished from economic affordability, as they are not mutually exclusive. For vaccines, C/E is dictated by several factors, including severity of disease, vaccine price, durability and efficiency.
Das et al. constructed a Markov model using decision analysis techniques to evaluate three different strategies regarding the early form of HEV vaccination in a Monte Carlo simulation cohort of 10 000 healthy young individuals living in endemic areas: A- Universal vaccination, B- Screening and vaccination, and C- No vaccination. The cost of illness consisted of the direct cost of treatment, as well as the indirect cost of lost workdays. Vaccine-induced immunity was presumed to last at least 8 years. Outcome parameters consisted of the incremental cost-effectiveness ratio, as well as the discounted cost per patient and quality adjusted life years (QALY) gained in each strategy. The cost-effectiveness (C/E) ratio for plans A, B, and C was $0.33, $0.50, and $0.53 respectively. The authors estimated the cost of vaccine to be $ 9.86 which is almost half of the anticipated price of Hecolin®. Based on the previous data, it seems that universal vaccination against HEV could be highly cost-effective with a marginal cost-effectiveness ratio below the currently available viral hepatitis vaccines. However, a Markov model analysis based on Hecolin® is needed, when additional data become available.
Areas for Future Research
Further research is needed to determine the titre of antibodies required for protection, the duration of protection afforded by the vaccine, the need for vaccine booster, and whether the vaccine is effective, not only against overt clinical illness, but also against all HEV infections.
Mitigating clinical infection and symptomatic disease, and decreasing the development of liver failure may be advantageous, even in the absence of infection prevention. Moreover, studies are needed to determine whether the vaccine would be useful for post-exposure prophylaxis, such as in cases of HEV outbreaks. Additionally, despite the serologic cross-reactivity, the efficacy of the vaccine has not been studied in regions of the world with HEV genotype 3, which has emerged as the predominant HEV strain in Europe and North America.
Additional data is needed regarding the safety and efficacy of this vaccine in individuals at extremes of age (younger than 2 years and older than 65 years), in pregnant women, and patients with chronic liver disease, as well as in immunosuppressed patients.
Preliminary evidence showed safety of the Hecolin® vaccine in pregnant women; 37 women who received 1, 2 or 3 doses of the vaccine turned out to be pregnant at time of administration. The vaccine was well-tolerated, and the delivered babies were healthy. These findings should be confirmed in larger studies.
Cost-effectiveness (C/E) of the vaccine should also be explored. C/E of an intervention is defined as the additional cost required per additional unit of health benefit produced as compared with the next-most effective alternative; this must be distinguished from economic affordability, as they are not mutually exclusive. For vaccines, C/E is dictated by several factors, including severity of disease, vaccine price, durability and efficiency.
Das et al. constructed a Markov model using decision analysis techniques to evaluate three different strategies regarding the early form of HEV vaccination in a Monte Carlo simulation cohort of 10 000 healthy young individuals living in endemic areas: A- Universal vaccination, B- Screening and vaccination, and C- No vaccination. The cost of illness consisted of the direct cost of treatment, as well as the indirect cost of lost workdays. Vaccine-induced immunity was presumed to last at least 8 years. Outcome parameters consisted of the incremental cost-effectiveness ratio, as well as the discounted cost per patient and quality adjusted life years (QALY) gained in each strategy. The cost-effectiveness (C/E) ratio for plans A, B, and C was $0.33, $0.50, and $0.53 respectively. The authors estimated the cost of vaccine to be $ 9.86 which is almost half of the anticipated price of Hecolin®. Based on the previous data, it seems that universal vaccination against HEV could be highly cost-effective with a marginal cost-effectiveness ratio below the currently available viral hepatitis vaccines. However, a Markov model analysis based on Hecolin® is needed, when additional data become available.
Source...