Longhorn Advances a Scalable Universal Flu Vaccine

Jeff Fisher, MBA

Longhorn Vaccines and Diagnostics has introduced a novel single-composite peptide vaccine that offers broad protection against human, avian, and swine influenza strains including pandemic variants such as H5N1. The unconjugated vaccine combines highly conserved epitopes from key influenza proteins, hemagglutinin (HA), neuraminidase (NA), and matrix proteins (M1, M2, M2e), with the ALFQ adjuvant to stimulate a strong immune response.

When Contagion first spoke with Jeff Fischer, president of Longhorn Vaccines & Diagnostics, in November 2024, he described the vaccine as a simplified, scalable formulation designed for global immunization efforts. In preclinical trials, the vaccine demonstrated robust serum IgG1 antibody responses, effectively neutralizing and inhibiting hemagglutination in both Group 1 and Group 2 influenza viruses. The inclusion of a universal T cell epitope further supports the development of long-term immune protection.

In this Q&A from ESCMID 2025, Fisher shares updates on the vaccine’s preclinical performance, its potential role in pandemic preparedness, and the path forward toward human trials.

Q: The LHNVD-110 vaccine shows broad strain coverage in pigs. What data can you share about its efficacy and safety in these models, and how confident are you that these results will translate to human populations?

Fischer: “The pig data we are presenting at ESCMID matches our previous data in mice. In both pigs and mice, the vaccine consistently generates high, durable IgG levels that bind and neutralize across influenza strains. There has also been no sign of reactogenicity. We look forward to future possibilities to study LHNVD-110 in humans with the goal of replicating results in mice and pigs.”

Q: Given the global burden of both influenza and COVID-19, what role could a universal vaccine play in pandemic preparedness?

Fischer: “A universal vaccine could play multiple roles in pandemic preparedness. It could be stockpiled for deployment once a pandemic strain is identified, providing at least a baseline level of protection while a strain-specific vaccine is developed. It could also replace the seasonal vaccine to generate coverage in advance of a pandemic and potentially prevent pandemics from ever happening.”

Q: How does the LHNVD-110 vaccine compare to currently available seasonal flu vaccines?

Fischer: “LHNVD-110 durability and consistency across strains suggests it should have significant advantages over current seasonal vaccines. As a composite peptide vaccine, it is easy to scale manufacturing. The likely durability of a year or more would allow the vaccine to be administered at any time during the year, as compared to the seasonal vaccine that must be closely timed to the expected flu season. For a vaccine manufacturer, manufacturing can be spread out over the year, and unused doses can be carried over from year to year, which also eliminates waste.”

Q: What are the next steps for these vaccine candidates, involving plans for human clinical trials and trial design?

Fischer: “LHNVD-110 generates monoclonal antibodies that have been modified for extended half-life, so the vaccine will likely proceed into clinical trials. The objective will be to demonstrate the targeted epitopes’ effectiveness in providing immunocompromised patients potent protection against influenza and COVID-19 that is not currently available. As a cocktail, those antibodies are expected to move into IND-enabling studies in the second half of 2025. The vaccine will follow and could be expedited if concerns grow over a pandemic.”

Q: How does considering both human and animal health in the design of these vaccines influence your target strategy for emerging infectious diseases?

Fischer: “Our One Health perspective covers global populations of humans and animals. Targeting multiple antigens on the influenza virus allows the vaccine to provide broad species protection and overcome viral mutations. Our vaccine design is easily scalable to allow for cost-effective immunization for large populations of humans or animals. It can be scaled regionally to bring production and access to both the Developed and Developing World.”