Recombinant RBD-based subunit vaccines incorporating high-frequency mutation sites elicit cross-immunity and robust protection against SARS-CoV-2

IntroductionSevere Acute Respiratory Syndrome Coronavirus type 2 (SARS-CoV-2), a highly pathogenic coronavirus (CoV) belonging to Coronavirus B, has triggered outbreaks or pandemics. Currently, many variants of SARS-CoV-2 have evolved, which exhibit severe immune evasion and imprinting resistance to existing vaccines and cause infected individuals to develop Post-Acute Sequelae of SARS-CoV-2 (also termed Long-COVID). This underscores the public health importance of developing effective vaccines