On Feb. 25, 2021, Altimmune announced that it had commenced enrollment in a Phase 1 clinical trial of AdCOVID, a single-dose intranasal COVID-19 vaccine candidate. AdCOVID is an adenovirus-vector vaccine designed to stimulate a broad immune response including both systemic immunity (neutralizing antibody) and local immunity (mucosal IgA and resident memory T cells) in the nasal cavity and respiratory tract.