Immunogenicity and safety of HBAI20 Hepatitis B vaccine in non-responders: Double-blinded, randomised, controlled phase 2 trial

Effectiveness of oral levamisole as an adjuvant to hepatitis B vaccination in healthcare workers non-responsive to previous vaccination: A randomized controlled trial

Background

Healthcare workers are at risk for HBV infection through percutaneous or mucosal contact with infected blood, body secretions, or blood products or via sharps injury. Hepatitis B vaccination, despite immunogenicity, may not induce a proper immune response in 5-10% of the general adult population. Increased immune response in healthcare providers that do not respond properly to conventional hepatitis B vaccination is an important health challenge. Therefore, the aim of the present study was to evaluate the effectiveness of hepatitis B vaccination plus oral levamisole as adjuvant in healthcare providers non-responsive to routine vaccination.

Materials and methods

The healthcare workers that were non-responsive to previous hepatitis B vaccination were enrolled in a double-blind randomized placebo-controlled clinical trial. The participants were then randomized to two groups including hepatitis B vaccination (as a three-dose series on a 0, 1, and 2-month schedule in the deltoid muscle) plus levamisole (levamisole group) and hepatitis B vaccination plus placebo (placebo group) at a 1:1 ratio. The outcome measure was the HBs antibody titer one month after receiving each dose as well as the seroprotection ratio. The side effects were also evaluated in all participants.

Results

In total, 22 subjects finished the trial (11 individual in per group). The median antibody titer one month after receiving the first and third doses increased more in the levamisole group compared to the placebo group but the difference was not significant (p ​= ​0.34, p ​= ​0.66, respectively).The seroprotection ratio after three doses was similarly high in both groups (90.9% in per group). Furthermore, the seroprotection ratio and median antibody titer had no significant correlation with age, sex, BMI, and history of smoking in intervention and control groups (p>0.05). No serious side effects were noted in both groups.

Conclusions

Re-vaccination can boost the immune response in healthcare professionals that were non-responsive to previous vaccination although the mean antibody titer was higher in the levamisole group.

The magnitude of the germinal center B cell and T follicular helper cell response predicts long-lasting antibody titers to plague vaccination

The development of a safe and effective vaccine against Yersinia pestis, the causative organism for plague disease, remains an important global health priority. Studies have demonstrated effective immune-based protection against plague challenge that is induced by plague antigen subunit vaccination in an aqueous alhydrogel formulation; however, whether these candidate vaccines in this formulation and presentation, induce long-lasting immunological memory in the form of durable cellular and antibody recall responses has not been fully demonstrated. In this study, we analyzed germinal center T follicular helper and germinal center B cell responses following F1V and F1 + V plague subunit immunization of mice with vaccines formulated in various adjuvants. Our data demonstrate that recombinant plague protein immunization formulated with IL-2/GM-CSF cytokines bound to alhydrogel adjuvant drive an increase in the magnitude of the germinal center T follicular helper and germinal center B cell responses following primary immunization, compared to vaccines formulated with Alhydrogel adjuvant alone. In contrast, plague protein subunit immunization combined with CpG ODN bound to alhydrogel increased the magnitude and duration of the germinal center Tfh and B cell responses following booster immunization. Importantly, enhanced germinal center Tfh and B cell responses correlated with long-lasting and high F1V-specific antibody titers and more robust antibody recall responses to F1V re-exposure. These findings indicate that vaccine formulations that drive enhancement of the germinal center Tfh and B cell responses are critical for inducing durable plague-specific humoral immunity.

Timing of primary three dose hepatitis B vaccination and postvaccination serologic testing among a large cohort of healthy adults

This study evaluated the optimal timing of a primary three‐dose hepatitis B vaccination and postvaccination serologic testing (PVST) among a large group of healthy naïve adults in the Netherlands. Data were collected from the Ease Travel Clinic hepatitis B vaccination database. The study population consisted of 22,997 adults who received three hepatitis B vaccinations. Seroprotection was attained in 97.3% individuals. When compared with PVST performed at 1–2 months (98.2%) after the final dose, lower seroprotection rates were observed with <1 (97.3%, p = 0.128), 3–6 (90.6%, p < 0.001), and ≥7 (88.4%, p < 0.001) months after vaccination. Among the subpopulation with a PVST 1–2 months, no statistically significant difference was observed for the various intervals between the first and second vaccination (<1, 1–2, 3–4, or ≥5 months). When compared with 4–5 months between the second and third vaccine dose, lower seroprotection rates were observed with <4 (odds ratio [OR]: 0.29, p = 0.020) and ≥12 (OR: 0.22, p < 0.001) months, although comparable rates were observed with 6–11 months interval (OR: 0.85, p = 0.262). Our data indicate that PVST should be obtained 1–2 months after the last vaccination and a delayed PVST was the major determinant of a lower seroprotection rate after primary three‐dose hepatitis B vaccination schedule. Based on our data, the hepatitis B vaccination also leaves room for flexibility for the second dose and the third dose without the necessity of restarting the vaccination series or confirmation of the immune response to the vaccine.