A phase I randomized, placebo-controlled, double-blind clinical trial revealed that V-01 (a recombinant interferon-armed receptor-binding-domain [RBD] dimer vaccine) is safe, has good tolerability, and is capable of eliciting strong and rapid immune responses. This study was carried out to explore the safety, immunogenicity and tolerability of recombinant COVID-19 vaccine (V-01) in healthy adults (young adults aged between 18 and 59 years and older adults over 60 years).

Participants were randomized into 3 subgroups for receiving V-01 (10, 25, and 50 μg) or placebo. The doses were intramuscularly administered with a 21-day interval and dose escalation manner. The findings revealed a favorable safety profile with about 25% vaccine-associated overall noxious events within 30 days and no grade III or worse side effects.

Furthermore, the vaccine triggered robust immune responses, induced considerably elevated-titre neutralizing antibodies and the anti-RBD IgG peaked at day thirty-five or forty-nine following the 1^st dose. Additionally, the vaccine exhibited favorable immunogenicity at the low dose subgroup (10 μg) and older adults, which demonstrated an enormous potential to be utilized as an all-aged (eighteen and above) vaccine against SARS-CoV-2. V-01 warrants additional research in Phase II/III clinical trials, concluded the study authors.