High neutralizing antibody levels against SARS-CoV-2 Omicron BA.1 and BA.2 after UB-612 vaccine booster

The highly transmissible Omicron variant has caused high rates of breakthrough infections in those previously vaccinated with ancestral strain COVID-19 vaccines. Here, we demonstrate that a booster dose of UB-612 vaccine candidate delivered 7-9 months after primary vaccination increased neutralizing antibody levels by 131-, 61- and 49-fold against ancestral SARS-CoV-2, Omicron BA.1, and BA.2 variants, respectively. Based on the RBD protein-binding antibody responses, the UB-612 third dose booster may lead to an estimated ∼95% efficacy against symptomatic COVID-19 caused by the ancestral strain. Our results support UB-612 as a potential potent booster against current and emerging SARS-CoV-2 variants.