Vivaldi Biosciences, a clinical-stage biotechnology company developing advanced vaccines for seasonal and pandemic influenza, recently announced the publication of Phase 1 clinical trial results for its deltaFLU vaccine for protection against influenza H5N1, a strain with pandemic potential. The data published in the journal Vaccine show that Vivaldi’s deltaFLU H5N1 vaccine induced a superior antibody response with a single intranasal dose.

H5N1 avian influenza/CDC

The Phase 1 clinical trial demonstrated that 75% of the study volunteers achieved seroconversion (a 4-fold or greater increase in serum hemagglutination inhibition assay [HAI] H5N1 antibody levels) after one intranasal dose of the deltaFLU H5N1 vaccine. After two doses of deltaFLU, 92% of the volunteers achieved a 4-fold or greater increase in HAI antibody levels.

The results of the Phase 1 study of deltaFLU H5N1 compare favorably with manufacturers’ data for the two influenza H5N1 vaccines licensed by the US Food & Drug Administration (FDA). The licensed vaccines are administered by intramuscular injection in a two-dose regimen. In reported clinical studies of the licensed vaccines, neither vaccine achieved 75% seroconversion with the first dose.

Vivaldi’s high-efficiency, high-yield Vero cell production system can make deltaFLU vaccines available for distribution within 7 weeks of the declaration of an influenza pandemic. The vast majority of vaccines for seasonal and pandemic influenza are produced in chicken eggs. Traditional egg-based production takes up to 6 months, and may induce antigenic changes that reduce vaccine efficacy. The emergence of an avian influenza strain with pandemic potential could jeopardize egg-based production.