Zosano Pharma Corporation announced the publication of Phase 1 clinical trial data in an article titled, “Immunogenicity and Safety of Inactivated Influenza Split-Virion Vaccine Administered via a Transdermal Microneedle System” in the Journal of Vaccines and Immunology. The data demonstrated that a low dose of a trivalent influenza vaccine administered via its transdermal microneedle system produced antibody levels that met EMEA's three guidelines for influenza vaccine efficacy and was generally well tolerated. The single-center, randomized Phase 1 study enrolled 90 subjects between the ages of 18 to 40 years to receive a trivalent influenza vaccine containing strains A/H1N1, A/H3N2, and B. Volunteers were randomized to receive the vaccine either via a transdermal microneedle system patch (10 g) worn for 5 minutes, the same patch worn for 15 minutes, or by intramuscular injection (15 g).

Antibody levels were measured at Day 21 and compared to EMEA guidelines to assess immunogenicity of the treatment groups. All three EMEA criteria, including seroconversion rate, mean increase in hemagglutinin inhibition titer, and percentage of seroprotected subjects, were met for all three influenza strains in all treatment groups. Additionally, on day 21, most study participants considered microneedle patch application and removal to be less painful than intramuscular injection, and most considered the patch to be their first choice for mode of administration.

The transdermal microneedle patch was generally well tolerated.