A Phase 2/3 double blinded, randomized, placebo-controlled study in healthy adult participants in Vietnam to examine the safety and immunogenicity of an inactivated whole virion, alum adjuvanted, A(H5N1) influenza vaccine (IVACFLU-A/H5N1)

Pandemic preparedness through vaccine development for avian influenza viruses

Influenza A viruses pose a significant threat to global health, impacting both humans and animals. Zoonotic transmission, particularly from swine and avian species, is the primary source of human influenza outbreaks. Notably, avian influenza viruses of the H5N1, H7N9, and H9N2 subtypes are of pandemic concern through their global spread and sporadic human infections. Preventing and controlling these viruses is critical due to their high threat level. Vaccination remains the most effective strategy for influenza prevention and control in humans, despite varying vaccine efficacy across strains. This review focuses specifically on pandemic preparedness for avian influenza viruses. We delve into vaccines tested in animal models and summarize clinical trials conducted on H5N1, H7N9, and H9N2 vaccines in humans.

Accelerate vaccine development using seamless phase 2/3 trial designs

BACKGROUND

Traditional vaccine development, often a lengthy and costly process of three separated phases. However, the swift development of COVID-19 vaccines highlighted the critical importance of accelerating the approval of vaccines. This article showcases a seamless phase 2/3 trial design to expedite the development process, particularly for multi-valent vaccines.

RESEARCH DESIGN AND METHODS

This study utilizes simulation to compare the performance of seamless phase 2/3 design with that of conventional trial design, specifically by re-envisioning a 9-valent HPV vaccine trial. Across three cases, several key performance metrics are evaluated: overall power, type I error rate, average sample size, trial duration, the percentage of early stop, and the accuracy of dose selection.

RESULTS

On average, when the experimental vaccine was assumed to be effective, the seamless design that performed interim analyses based solely on efficacy saved 555.73 subjects, shortened trials by 10.29 months, and increased power by 3.70%. When the experimental vaccine was less effective than control, it saved an average of 887.73 subjects while maintaining the type I error rate below 0.025.

CONCLUSION

The seamless design proves to be a compelling strategy for vaccine development, given its versatility in early stopping, re-estimating sample sizes, and shortening trial durations.

Preclinical immunogenicity assessment of a cell-based inactivated whole-virion H5N1 influenza vaccine

In influenza vaccine development, Madin–Darby canine kidney (MDCK) cells provide multiple advantages, including large-scale production and egg independence. Several cell-based influenza vaccines have been approved worldwide. We cultured H5N1 virus in a serum-free MDCK cell suspension. The harvested virus was manufactured into vaccines after inactivation and purification. The vaccine effectiveness was assessed in the Wuhan Institute of Biological Products BSL2 facility. The pre- and postvaccination mouse serum titers were determined using the microneutralization and hemagglutination inhibition tests. The immunological responses induced by vaccine were investigated using immunological cell classification, cytokine expression quantification, and immunoglobulin G (IgG) subtype classification. The protective effect of the vaccine in mice was evaluated using challenge test. Antibodies against H5N1 in rats lasted up to 8 months after the first dose. Compared with those of the placebo group, the serum titer of vaccinated mice increased significantly, Th1 and Th2 cells were activated, and CD8+ T cells were activated in two dose groups. Furthermore, the challenge test showed that vaccination reduced the clinical symptoms and virus titer in the lungs of mice after challenge, indicating a superior immunological response. Notably, early after vaccination, considerably increased interferon-inducible protein-10 (IP-10) levels were found, indicating improved vaccine-induced innate immunity. However, IP-10 is an adverse event marker, which is a cause for concern. Overall, in the case of an outbreak, the whole-virion H5N1 vaccine should provide protection.

Isothermal nucleic acid amplification technology for rapid detection of virus

While the research field and industrial market of in vitro diagnosis (IVD) thrived during and post the COVID-19 pandemic, the development of isothermal nucleic acid amplification test (INAAT) based rapid diagnosis was engendered in a global wised large measure as a problem-solving exercise. This review systematically analyzed the recent advances of INAAT strategies with practical case for the real-world scenario virus detection applications. With the qualities that make INAAT systems useful for making diagnosis relevant decisions, the key performance indicators and the cost-effectiveness of enzyme-assisted methods and enzyme-free methods were compared. The modularity of nucleic acid amplification reactions that can lead to thresholding signal amplifications using INAAT reagents and their methodology design were examined, alongside the potential application with rapid test platform/device integration. Given that clinical practitioners are, by and large, unaware of many the isothermal nucleic acid test advances. This review could bridge the arcane research field of different INAAT systems and signal output modalities with end-users in clinic when choosing suitable test kits and/or methods for rapid virus detection.

Persistence of vaccine-induced antibody to A/H5N1 influenza after 30 and 36 months of vaccination

Objectives

An A/H5N1 vaccine named IVACFLU-A/ H5N1 was accepted to use in Vietnam, however, antibody persistence after vaccination has not been well characterized yet. We examined the persistence of antibodies after vaccination and related risk factors in individuals enrolled in phase II with 15 mcg dose, 2 injections 21 days apart, IVACFLU-A/ H5N1 vaccine trials in Ninh Hoa, Vietnam.

Methods

We used a longitudinal study to follow 86 participants without control groups. They were tested anti-A/H5N1 IgG seronegative at baseline and received all two doses of the vaccine. Blood was drawn at 30 and 36 months after the full vaccination to assess antibody status. Antibody persistence status is compared by demographics and exposure risk factors using a univariate logistic regression.

Results

Overall incidence of persisting at least 1/10 of A/H5N1 antibodies was 84.9% and 52.3% after 30 months and 36 months of IVACFLU-A/H5N1 vaccination. The odds of antibody persistence were more significant in older people but lower in people who experienced flu-like symptoms in the past 18 months or between two visits. We recorded no differences between A/H5N1 antibodies persistence and exposure risk factors including having poultry farms, contacting with poultry, and slaughtering and processing poultry.

Conclusion

This study demonstrated noteworthy antibody persistence, indicated by seroconversion rate and geometric mean titer at 30 and 36-month post-vaccination, of the IVACFLU-A/H5N1 vaccine. There is a need for further studies on older people, and those who experienced flu-like symptoms to decide the suitable time for the booster shot.

Hydroxypropyltrimethyl ammonium chloride chitosan-based hydrogel as the split H5N1 mucosal adjuvant: Structure-activity relationship

In this study, 2-hydroxypropyltrimethyl ammonium chloride chitosan (HTCC)-based hydrogel was devised as a mucosal adjuvant for H5N1 vaccine. Aimed to investigate the structure activity relationship between HTCC hydrogel and immune response, we prepared a series of HTCC hydrogel with defined quaternization degrees (DQs, 0%, 21%, 41%, 60%, 80%). Results suggested that with DQ increasing, the positive charge and gelation time of HTCC hydrogel increased but the viscosity decreased. We applied in vivo imaging system and found that the moderate DQ 41% prolonged antigen residence time in nasal cavity, resulting in the most potent systemic responses (IgG, IgG1, IgG2a, HI). While, the lowest DQ 0% produced the best mucosal IgA antibody responses, most likely due to the closer contact with mucosa. Furthermore, the influence of animal gender was also discussed. These data add to the growing understanding of the relationship between physicochemical features of chitosan-based hydrogel and how they influence the immune responses.