Abstract
Omicron, a highly transmissible SARS-CoV-2, emerged in November 2021. The high mutation rates within spike protein of Omicron raised concerns about increased breakthrough infections among the vaccinated. We tested cross-reactivity of antibodies induced by UB-612 against Omicron and other variants. After 2 doses, UB-612 elicited low levels of neutralization antibodies against ancestral virus and Omicron. A booster dose delivered 7-9 months after primary vaccination dramatically increased antibody levels, with only a 1.4-fold loss in neutralization titer against Omicron compared to the ancestral strain. Using a model bridging vaccine efficacy with ancestral virus RBD binding antibody responses, predicted efficacy against symptomatic COVID-19 after UB-612 booster is estimated at 95%. UB-612 is anticipated to be a potent booster against current and emerging SARS-CoV-2 variants.
One-Sentence Summary UB-612 booster induced broadly neutralizing antibodies against Omicron and is presumed to be protective against COVID-19.
Competing Interest Statement
FG, SW, LW, MMH, TM and AR are employees at Vaxxinity, Inc, Dallas, TX, USA. CYW, WJP, and HL are employees at United Biomedical Inc Asia, Taipei, Taiwan.
