Intranasal COVID-19 vaccine candidate shows sterilizing immunity in preclinical tests

University of Alabama at Birmingham researchers report additional preclinical evidence of the potency of a single-dose, intranasal COVID-19 vaccine candidate—AdCOVID—that was created by Altimmune Inc., a Maryland-based clinical-stage biopharmaceutical company.

The UAB researchers, led by Fran Lund, Ph.D., in collaboration with Altimmune, have found that a single intranasal dose provided sterilizing immunity in the lungs of vaccinated animals. In contrast, the lungs of non-vaccinated animals showed dense pulmonary infection and disease following infection with SARS-CoV-2, the virus that causes COVID-19.

«In the current study,» said Scot Roberts, Ph.D., chief scientific officer at Altimmune, «we found a heavy burden of infectious SARS-CoV-2 virus in the lungs of non-vaccinated mice following challenge with the virus. Importantly, no infectious virus could be detected in the lungs of AdCOVID-vaccinated animals. These data suggest that a single intranasal vaccination with AdCOVID can provide sterilizing immunity that neutralizes infectious virus, which is believed to be the best way to block viral transmission.

«Blocking transmission is critical for preventing spread of the virus and preventing the emergence of new variants of concern, both of which have the potential to prolong the pandemic,» Roberts said.

AdCOVID is currently in a Phase 1 clinical trial to test safety and immunogenicity in people, and Altimmune expects to report topline data in June.

«Growing vaccine hesitancy is emerging as a real problem in the fight against SARS-CoV-2,» said Lund, the Charles H. McCauley Professor and chair for the UAB Department of Microbiology. This underscores the importance of developing novel vaccine approaches like AdCOVID, which is well-tolerated, needle-free and thermostable, can be delivered in a single dose, and has the potential to prevent SARS-CoV-2 transmission.

«These attributes could foster vaccine acceptance, both nationally and globally,» Lund said. «In addition, intranasally delivered AdCOVID could play a critical role in re-vaccination campaigns to control future spread of the virus, and ultimately help bring an end to this devastating global pandemic.»

The COVID-19 pandemic—with more than 3.25 million global deaths—has highlighted the urgent need for effective preventive vaccination to reduce the burden and spread of the virus.

Last spring and summer, Lund and 23 other researchers from six labs in the UAB School of Medicine tested AdCOVID preclinically. Working under strict COVID-19 safety protocols that required masking and social distancing, the UAB researchers found potent serum-neutralizing antibody responses, T cell responses and a robust induction in mucosal immunity in mice following a single intranasal dose of AdCOVID.

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