Despite the fact that hepatitis B vaccines have been available for more than two decades, infection with the hepatitis B virus (“HBV”) remains a worldwide health problem. Globally, more than two billion individuals present with serological evidence of HBV infection. Of these, 240 million are chronic carriers and approximately 780,000 hepatitis B-related deaths occur annually.
Second-generation hepatitis B vaccines, which use an HBV surface antigen, the S antigen, to create an immunologic response in vaccine recipients, have been shown to have good efficacy in preventing infection, however, many individuals do not respond to these currently licensed vaccines. Hepatitis B vaccine failure is often explained by immunosenescence (the gradual deterioration of the immune system brought on by aging) and immunosuppression, or by comorbidities such as obesity, renal failure, HIV infection, and diabetes.
About Hepatitis B
Hepatitis B Vaccine Approaches
Nearly 30 million people in the United States have diabetes mellitus. Diabetes is a condition characterized by high blood sugar levels, due to an inability to absorb sugar and use it as energy. Diabetes can lead to a number of complications including susceptibility to infections, kidney failure, blindness, nerve damage, cardiovascular disease, and non-traumatic amputation. Diabetes is the seventh leading cause of death in the U.S.
Persons with diabetes have higher rates of hepatitis B than the general population and are at an increased risk of infection. Seroprevalance of the HBV core antigen (suggesting past or current infection) is 60% higher among adults with diabetes than those without diabetes. U.S. Centers for Disease Control and Prevention (“CDC”) analysis suggests that the risk of acute HBV infection is twice as high among adults with diabetes aged 23+ compared to adults without diabetes. Moreover, following acute infection, persons with diabetes are at an increased risk of developing chronic hepatitis B compared to otherwise healthy adults.
Since 2011, the CDC’s Advisory Committee on Immunization Practices (“ACIP”) has recommended that all previously unvaccinated adults with diabetes aged 19 to 60 years be vaccinated as soon as possible following a diabetes diagnosis, and that vaccination be considered for those aged 60+. Despite this recommendation, research suggests that improved hepatitis B vaccine options for persons with diabetes may be beneficial.
Persons with diabetes have a poor response rate to conventional vaccination
Persons with diabetes are less responsive to second-generation hepatitis B vaccination than healthy adults. Studies examining a second-generation hepatitis B vaccine approved for use in the U.S. showed response rates as low as 54% in diabetic persons.
Vaccination coverage is low in persons with diabetes
The CDC estimates that the current hepatitis B vaccination coverage for persons with diabetes was only 26.3% for those aged 19 to 59 years. The rate is lower for those 60+ at 13.9%.
Vaccine effectiveness decreases as persons with diabetes age
When the antibody responses among older adults with and without diabetes are compared, the response rates were reduced among persons with diabetes. CDC research has shown that in individuals between 41 and 59 years of age, the response rate to vaccination was as high as 80%, but quickly dropped to 65% after age 60 and under 40% in individuals 70+. Studies examining a second-generation hepatitis B vaccine have shown that efficacy in diabetic persons progressively declines with advancing age.
Diabetic persons with obesity are at increased risk
Host factors (smoking, obesity, genetic factors, and immune suppression) and comorbid conditions all decrease the likelihood of a vaccine response. Obesity is a major risk factor for type 2 diabetes and 56% of adults with diabetes are obese. Studies have demonstrated an association between obesity and reduced response to the hepatitis B vaccine in adults, suggesting obese persons with diabetes are less likely to respond to vaccination.
Diabetes can impair vaccine responsiveness in chronic conditions
Diabetes is one of the leading causes of kidney failure. In persons with end-stage renal disease (“ESRD”), diabetes is independently associated with failure to achieve HBV seroprotection.
The biological basis for the impaired response to vaccination among persons with diabetes is still under investigation. It is hypothesized that the compromised immune system in individuals with diabetes leads to an impaired cellular response. Interestingly, analysis has shown that there is no association between glycemic control, the duration of diabetes, or insulin requirements and resultant seroprotection after hepatitis B vaccination.
To increase seroprotection rates for diabetic persons, various strategies have been researched including augmented dosing schedules, additional and/or higher doses of the hepatitis B vaccine, combination vaccinations, novel adjuvants, and recombinant third-generation vaccines.
Sci-B-Vac™: A Third-Generation Hepatitis B Vaccine
To overcome the potential limitations of the second-generation, yeast-derived vaccines, VBI developed a third-generation vaccine that contains the S, pre-S1 and pre-S2 surface antigens. The composition of Sci-B-Vac™ may provide more opportunities for the immune system to respond with antibodies that can recognize one or more components of the hepatitis B virus.
To learn more about Sci-B-Vac™, visit: https://www.vbivaccines.com/sci-b-vac/