On May 10, 2021, Altimmune announced positive results from a preclinical study of AdCOVID in a SARS-CoV-2 challenge model of infection. In this study, a single intranasal dose of AdCOVID provided sterilizing immunity in the lungs of vaccinated mice, in contrast to the development of dense pulmonary infection and disease in the lungs of non-vaccinated mice following infection with SARS-CoV-2.