SARS-CoV-2, the causal agent of the COVID-19 pandemic, is characterized by rapid evolution, which poses a significant public health challenge. Effective vaccines that provide robust protection, elicit strong immune responses, exhibit favorable safety profiles, and enable cost-effective large-scale production are crucial. The RBD-Fc-based Betuvax-CoV-2 vaccine has previously demonstrated a favorable safety profile and induced a significant anti-SARS-CoV-2 humoral immune response in clinical trials. Due to the rapid evolution and emergence of new SARS-CoV-2 strains, the relevance of bivalent vaccine formulations has increased. Methods: This study compared the neutralizing capacity of monovalent and bivalent vaccine formulations against different SARS-CoV-2 strains detected with a SARS-CoV-2 microneutralization assay (MNT). Findings: The monovalent Wuhan-based vaccine generated neutralizing antibodies against the Wuhan and Omicron BA.2 variants but not the distinct Omicron BQ.1 strain. Conversely, the monovalent BA.2-based vaccine induced neutralizing antibodies against both Omicron strains but not Wuhan. While the bivalent Wuhan and BA.2-based vaccine was effective against strains containing the same antigens, it was insufficient to neutralize the distinctive BQ.1 strain at a small dosage. Interpretation: These findings suggest that the vaccine composition should closely match the circulating SARS-CoV-2 strain to elicit the optimal neutralizing antibody response and include the appropriate dosage. Moreover, this study did not find additional advantages of using the bivalent form over the monovalent form for the vaccination against a single prevailing SARS-CoV-2 strain.