Safety and Immunogenicity of the Convacell ® Recombinant N Protein COVID-19 Vaccine.

We have developed Convacell ® -a COVID-19 vaccine based on the recombinant nucleocapsid (N) protein of SARS-CoV-2. This paper details Convacell's ® combined phase I/II and IIb randomized, double-blind, interventional clinical trials. The primary endpoints were the frequency of adverse effects (AEs) and the titers of specific anti-N IgGs induced by the vaccination; secondary endpoints included the nature of the immune response. Convacell ® demonstrated high safety in phase I with no severe AEs detected, 100% seroconversion by day 42 and high and sustained for 350 days anti-N IgG levels in phase II. Convacell ® also demonstrated a fused cellular and humoral immune response. Phase IIb results showed significant post-vaccination increases in circulating anti-N IgG and N protein-specific IFNγ + -producing PBMC quantities among 438 volunteers. Convacell ® showed same level of immunological efficacy for single and double dose vaccination regimens, including for elderly patients. The clinical studies indicate that Convacell ® is safe and highly immunogenic.