Human Metapneumovirus

Study VCA25397 is a Phase 2b, observer-blind, randomized, placebo-controlled, parallel, case-driven proof of concept study that will enroll approximately 8000 adults aged 60 years and older to assess the clinical efficacy, safety, and immunogenicity of a single IM (intramuscular) injection of the bivalent RSV+HMPV protein vaccine candidate. The study will include a Safety Lead-in Cohort that will be enrolled first and will comprise 200 participants aged 60 years and older randomized in a 1:1 ratio to receive either RSV+HMPV protein vaccine or placebo (100 participants per arm). The enrollment of the Main Cohort will start after the completion of the ESDR (Early Safety Data Review), pending a positive outcome. For the Main Cohort, 7800 participants (3900 participants per arm) will be randomized in a 1:1 ratio to receive either RSV+HMPV protein vaccine or placebo.