A Study to Evaluate the Safety and Immunogenicity of a Single Dose of H1ssF-3928 mRNA-LNP in Healthy Adults

This is a Phase 1, single-site, open-label, comparator-controlled dose escalating study of an intramuscularly (IM) administered mRNA-LNP vaccine encoding for (Vaccine Research Center) VRC H1ssF 3928 of up to 50 healthy adult volunteers aged 18 to 49 years, inclusive. This study is designed to assess the safety and immunogenicity of one dose of H1ssF 3928 mRNA Vaccine. Eligible participants will be sequentially enrolled into dosing groups (10 mcg, 25 mcg, and 50 mcg, selected optimal dose) to receive the H1ssF 3928 mRNA Vaccine at the specified dose. A separate group of 10 participants will receive licensed quadrivalent influenza vaccine (IIV4). Subjects receiving IIV4 will be followed for safety but only their immune responses will be compared to those of participants receiving H1ssF 3928 mRNA Vaccine. Dosing of H1ssF 3928 mRNA Vaccine will commence at the lowest dose (10 mcg) and only escalate to the next highest dose if safety concerns are not identified. Up to ten subjects will be enrolled per dosing cohort. Reactogenicity and adverse event (AE) information through Day 7 and clinical laboratory results through Day 8 from the first three dosing groups will guide the selection of an optimal dose group to include 10 subjects who will receive the optimal dose of mRNA-LNP. The primary objective of this study is to assess the safety of a single dose of VRC H1ssF 3928 mRNA-LNP vaccine administered IM in healthy adults, 18-49 yrs, at doses of 10 mcg, 25 mcg, and 50 mcg.