A Phase 2 Trial of the Immunogenicity and Safety of CVXGA Intranasal COVID Vaccine in Healthy Adults

This is a randomized, placebo controlled, blinded study to evaluate the immunogenicity and safety of CVXGA. Trial Population: Up to 400 healthy adults (18-80 years) that may have had prior COVID vaccination or COVID infection at least 5 months prior to planned study vaccine receipt. Vaccine: CVXGA is a recombinant parainfluenza virus type 5 (PIV5) that carries the SARS-CoV-2 S protein. The vaccine will be administered as a single intranasal dose as a spray. Study visits: Participants will be asked to complete 3 clinic visits and 1 follow-up phone call. Participants \>= 65 yrs of age will have an additional 2 clinic visits to test for vaccine shedding. Follow-up will be for 6 months after single vaccination.