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

(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