Fendrix® Vaccine Effectiveness in Healthcare Workers Who Are Non-Responsive to Engerix B® Vaccination

Using the AS04C-adjuvanted hepatitis B vaccine in patients classified as non-responders

BACKGROUND

Chronic hepatitis B (HB) remains a significant global health concern, despite the widespread availability of the HB vaccine. While the standard vaccine demonstrates an impressive serological response rate exceeding 90%, a subset of individuals exhibit suboptimal immunity. This study aims to elucidate the efficacy of the AS04C-adjuvanted HB vaccine in addressing non-responsiveness.

METHODS

Conducted at the Preventive Medicine Service of the University Albacete Hospital in Spain from 2017 to 2021, this single-center observational study enrolled 195 patients. Among them, 126 (65%) were classified as non-responders following one or two complete standard vaccination courses.

RESULTS

After the administration of a complete four-dose regimen of the AS04C-adjuvanted vaccine, 73.81% of non-responder patients exhibited antibody titers indicative of robust immunity (anti-HBs >10).

CONCLUSIONS

These findings underscore the pivotal role of the AS04C-adjuvanted HB vaccine in addressing non-responsiveness, emphasizing its potential as a crucial tool in augmenting immunization strategies for various populations. This includes non-responders to standard vaccination, individuals with chronic kidney disease, those requiring seroprotection due to factors like immunosuppression or occupational hazards, as well as patients for whom conventional revaccination strategies have proven futile. Additional research is needed to expand on the promising results obtained through our protocol.

Hepatitis B in Healthcare Personnel: An Update on the Global Landscape

Despite the outstanding progress that has been made in the prevention, detection, and management of hepatitis B during the past decades, hepatitis B remains a problem among healthcare personnel (HCP) in many countries. We reviewed studies on all aspects of hepatitis B in HCP published from 2017 through April 2023. They revealed wide variations on the prevalence of infection among HCP, ranging from 0.6% in Europe to >8.7% in Africa, almost always in association with very low vaccination rates. Many studies found a significant association between HCP's knowledge about hepatitis B and hepatitis B vaccines, their vaccination status, and practices. This research also discloses global inequities regarding vaccination policies against hepatitis B, free-of-charge vaccinations, and access to post-exposure prophylaxis (PEP). Strategies to prevent and manage accidental exposures are needed in order to reduce the burden of hepatitis B on HCP, while written policies for all aspects of infection prevention, protective equipment, and PEP should be available. Lastly, HCP should be accordingly educated. These are all imperative given the decline of routine vaccinations in the COVID-19 era, particularly in countries with fragile vaccination programs, and the disruptions of interventions for hepatitis B that are expected to provide a pool of virus transmission to future generations.

Progress towards Adjuvant Development: Focus on Antiviral Therapy

In recent decades, vaccines have been extraordinary resources to prevent pathogen diffusion and cancer. Even if they can be formed by a single antigen, the addition of one or more adjuvants represents the key to enhance the response of the immune signal to the antigen, thus accelerating and increasing the duration and the potency of the protective effect. Their use is of particular importance for vulnerable populations, such as the elderly or immunocompromised people. Despite their importance, only in the last forty years has the search for novel adjuvants increased, with the discovery of novel classes of immune potentiators and immunomodulators. Due to the complexity of the cascades involved in immune signal activation, their mechanism of action remains poorly understood, even if significant discovery has been recently made thanks to recombinant technology and metabolomics. This review focuses on the classes of adjuvants under research, recent mechanism of action studies, as well as nanodelivery systems and novel classes of adjuvants that can be chemically manipulated to create novel small molecule adjuvants.

TLR4 agonist activity of Alcaligenes lipid a utilizes MyD88 and TRIF signaling pathways for efficient antigen presentation and T cell differentiation by dendritic cells

Alcaligenes faecalis was previously identified as an intestinal lymphoid tissue-resident commensal bacteria, and our subsequent studies showed that lipopolysaccharide and its core active element (i.e., lipid A) have a potent adjuvant activity to promote preferentially antigen-specific Th17 response and antibody production. Here, we compared A. faecalis lipid A (ALA) with monophosphoryl lipid A, a licensed lipid A-based adjuvant, to elucidate the immunological mechanism underlying the adjuvant properties of ALA. Compared with monophosphoryl lipid A, ALA induced higher levels of MHC class II molecules and costimulatory CD40, CD80, and CD86 on dendritic cells (DCs), which in turn resulted in strong T cell activation. Moreover, ALA more effectively promoted the production of IL-6 and IL-23 from DCs than did monophosphoryl lipid A, thus leading to preferential induction of Th17 and Th1 cells. As underlying mechanisms, we found that the ALA-TLR4 axis stimulated both MyD88- and TRIF-mediated signaling pathways, whereas monophosphoryl lipid A was biased toward TRIF signaling. These findings revealed the effects of ALA on DCs and T cells and its induction pattern on signaling pathways.