A Beta-containing bivalent SARS-CoV-2 spike protein vaccine candidate with AS03 elicits durable and broad neutralization of variants including Omicron in macaques and confers protection in hamsters

Abstract Background Since the beginning of the COVID-19 pandemic, several variants of concern (VOC) have emerged for which there is evidence of an increase in transmissibility, more severe disease, and/or reduced vaccine effectiveness. Effective COVID-19 vaccine strategies are required to achieve broad protective immunity against current and future VOC.Methods We conducted immunogenicity and challenge studies in macaques and hamsters using a bivalent recombinant vaccine formulation containing the SARS-CoV-2 prefusion-stabilized Spike trimers of the parental D614 and the Beta (B.1.351) strains with AS03 adjuvant (CoV2 preS dTM-AS03) in a primary immunization setting. Results We show that a primary immunization with the bivalent CoV2 preS dTM-AS03 elicits broader and durable neutralizing antibody responses against VOC including Omicron BA.1, and SARS-CoV-1 as compared to the parental D614 or Beta variant monovalent vaccines in naïve non-human primates. In addition, the bivalent formulation confers protection against viral challenge with SARS-CoV-2 parental D614G strain as well as Alpha and Beta variant strains in hamsters. Conclusions Our findings demonstrate the potential of a Beta-containing bivalent CoV2 preS dTM-AS03 formulation to provide broad and stable immunogenicity, as well as protection against VOC in naïve populations.