Intranasal COVID-19 Vaccine Candidate Shows Potent Immune Responses in Extensive Preclinical Tests

An intranasal COVID-19 vaccine candidate that underwent extensive preclinical testing has shown potent preclinical immune responses, including several that distinguish it from other COVID-19 vaccine approaches.

Altimmune, Inc. (Gaithersburg, MD, USA) is collaborating with the University of Alabama (Birmingham, AL, USA) for clinical trials to evaluate its intranasal dose COVID-19 vaccine candidate, AdCOVID. AdCOVID is based on Altimmune’s adenovirus-based intranasal vaccine platform, and the vaccine candidate expresses the receptor binding domain of the SARS-CoV-2 spike protein. This domain is essential for viral infection, and the majority of neutralizing antibodies found in people who recovered from COVID-19 bind to this receptor binding domain, highlighting it as a target to control infection.

Following partial preclinical results announced in July and August, the latest expanded results show strong activation of both arms of the adaptive immune system following a single intranasal dose of Altimmune’s AdCOVID, as tested at UAB in two strains of mice. The vaccine potently stimulated neutralizing antibodies in the blood plasma that can inactivate SARS-CoV-2 as well as the immune system’s T cells, priming them to attack virus-infected cells. More importantly, the vaccine elicited mucosal antibody and T cell responses in the respiratory tract, including the lung and the nose, creating a possible barrier to infection and transmission at the viral point of entry. The observed IgA response, together with the lung-associated resident memory T cell response, provides an additional level of immune response, as compared to intramuscular vaccination, that may provide enhanced protection against COVID-19 disease and transmission.

Altimmune expects AdCOVID will have an important advantage over some other vaccine candidates that require freezers or ultra-low freezers during distribution. AdCOVID’s expected stability at room temperature would allow distribution without refrigeration, followed by long-term storage in simple refrigerators at clinics or pharmacies. Also, an intranasal inoculation does not require syringes or needles. Additionally, current first-generation COVID-19 vaccines that are given by intramuscular injection, are unable to activate nasal mucosal immunity. Nasal mucosal immunity may be critical for mounting a comprehensive immune response, and it may also prevent further spread of the virus by blocking transmission.

“Intranasal vaccination represents an attractive strategy to prevent COVID-19 infection, as the nasal cavity comprises the first-line of defense against the SARS-CoV-2 virus prior to entry into the lungs,” said Scot Roberts, Ph.D., chief scientific officer for Altimmune. “By stimulating mucosal antibody and T cell immunity, along with potent systemic neutralizing antibody titers, both arms of the immune system can work in concert to prevent and control infection.”

Related Links:
Altimmune, Inc.
University of Alabama