FLU-v is comprised of four synthetic peptides predicted in silico to cover heavily conserved immunogenic regions of influenza A and B viral proteins M1, M2 and NP-A and NP-B. These internal viral proteins evolve more slowly than the surface proteins traditionally targeted by classical influenza vaccines, which require updating every year. 

The FLU-v vaccine aims to elicit a broadly protective immune response through viral clearance by cytotoxic T cell release of pro-inflammatory cytokines, as well as perforin and granzyme. 

FLU-v has demonstrated safety, immunogenicity, and clinical efficacy in preclinical work and in Phase I and Phase II clinical studies. A Phase IIb H1N1 challenge trial in healthy adults observed a significant reduction in mild to moderate cases of influenza disease and fewer participants reporting two or more symptoms with FLU-v, compared to placebo.

Having met clinical efficacy and safety endpoints in Phase 1 and Phase 2 studies, FLU-v is now ready for Phase 3 development.

FLU-v clinical development 

Phase 1b safety and immuno study (Pleguezuelos et al, 2012, Vaccine)

  • Randomised, double-blind single-centre study in 48 healthy adults
  • Excellent safety and tolerability 
  • Strong vaccine-specific cell mediated immune response measured 21 days post-dose

Phase 1b H3N2 challenge study (Pleguezuelos et al, 2015, Clin Vaccine Immunol)

  • Randomised, double-blind, placebo-controlled, single-centre H3N2 influenza A challenge study in 32 healthy adults
  • FLU-v safe and well tolerated
  • Specific cell mediated immune responses correlated with significant reduction in viral load and symptom score post-challenge

Phase 2b field study (Pleguezuelos et al, 2020, Annals of Internal Medicine)

  • Randomised, double-blind, placebo-controlled, single-centre trial in 175 healthy adults 
  • Excellent safety and tolerability 
  • Strong vaccine-specific cell mediated immune response measured at 42 and 180 days post-dose.

Phase 2b H1N1 challenge study (Pleguezuelos et al, 2020, NPJ Vaccines)

  • A randomised, double-blind, placebo-controlled, single-centre H1N1 influenza A challenge study in 153 healthy adults to assess FLU-v efficacy and safety 
  • Primary objective met: significant reduction in mild to moderate influenza disease 
  • Significant reduction in number of participants with 2 or more symptoms
  • Mostly mild or moderate adverse events related to injection site reactions
  • No serious adverse events


FLU-v manufacture and storage

FLU-v vaccine peptides are synthesised using the egg-free Fmoc chemistry process and can be shipped and stored at room temperature in API lyophilised powder form for 3 months (up to 2 years at 20°C). The powder is then combined with non-metal based MontanideTM ISA-51 adjuvant and water for injection immediately prior to use.   


Key publications

Stoloff GA, Caparros-Wanderley W. Synthetic multi-epitope peptides identified in silico induce protective immunity against multiple influenza serotypes. Eur J Immunol, 2007, 37:9, 2441-9. doi: 10.1002/eji.200737254

Pleguezuelos et al. Synthetic Influenza vaccine (FLU-v) stimulates cell mediated immunity in a double-blind, randomised, placebo-controlled Phase I trial. Vaccine, 2012, 30:31, 4655-4660. doi: 10.1016/j.vaccine.2012.04.089

Pleguezuelos et al. A Synthetic Influenza Virus Vaccine Induces a Cellular Immune Response That Correlates with Reduction in Symptomatology and Virus Shedding in a Randomized Phase Ib Live-Virus Challenge in Humans. Clin Vaccine Immunol., 2015, 22:7; 828-35. doi: 10.1128/CVI.00098-15. 

Pleguezuelos et al. Immunogenicity, safety, and efficacy of a standalone universal influenza vaccine, FLU-v, in healthy adults. Annals of Internal Medicine, 2020, 172:7, 453-462. doi:10.7326/M19-0735

Pleguezuelos et al. Efficacy of FLU-v, a broad-spectrum influenza vaccine, in a randomized phase IIb human influenza challenge study. NPJ Vaccines, 2020, 5:22, doi: 10.1038/s41541-020-0174-9