Abstract
Adjuvants are key to shaping the immune response to vaccination, but to date, no adjuvant suitable for human use has been developed for intradermal vaccines. These vaccines could be self-administered and sent through the mail as they do not require long needles or technical expertise in immunization. In the event of a pandemic outbreak, this approach could alleviate the congregation of patients in health centers and thus reduce the potential of these centers to enhance the spread of lethal infection. A reliable and potent vaccine system for self-administration would provide an effective countermeasure for delivery through existing product distribution infrastructure. We report results from preclinical and clinical trials that demonstrate the feasibility of an adjuvanted, intradermal vaccine that induced single shot protection in ferrets and seroprotection in humans against one of the more lethal strains of pandemic flu, Indonesia H5N1. In the human trial, the vaccine was safe and clinical responses were above approvable endpoints for a protective flu vaccine. Inclusion of a modern TLR4 (Toll-like receptor 4) agonist-based adjuvant was critical to the development of the response in the intradermal groups. In humans, this is the first report of a safe and effective intradermal adjuvant, GLA-AF (aqueous formulation of glucopyranosyl lipid adjuvant), and provides a future path for developing a vaccine-device combination for distribution by mail and self-administration in case of a pandemic.