Zoonotic spillover of sarbecoviruses to humans resulted in theSARS-CoV-1 outbreak in 2003and the current COVID-19 pandemic caused by SARS-CoV-2. In both cases, the viral spikeprotein (S) is the principal target of neutralising antibodies that prevent infection. Within spike, the immunodominant receptor-binding domain (RBD) is the primary target of neutralising antibodies in COVID-19 convalescent sera and vaccine recipients. We have constructed stabilized RBD derivatives of different sarbecoviruses: SARS-CoV-1 (Clade 1a), WIV-1 (Clade 1a), RaTG13 (Clade 1b), RmYN02 (Clade 2) and BtKY72 (Clade 3). Stabilization enhanced yield by an 3-23-fold. The RBD derivatives were conformationally intact as assayed by binding to multiple broadly neutralizing antibodies. The stabilized RBDs show significant enhancement in apparent Tm, exhibit resistance to a 2-hour incubation at temperatures up to 60°C in PBS in contrast to corresponding WT RBDs, and show prolonged stability of over 15 days at 37°C after lyophilization. In mice immunizations, both stabilization and trimerization significantly enhanced elicited neutralization titers by ~100 fold. The stabilized RBD cocktail elicited high neutralizing titers against both homologous and heterologous pseudoviruses. The immunogenicity of the vaccine formulation was assessed in both naïve and SARS-CoV-2 pre-immunized mice, revealing an absence of immune imprinting, thus indicating its suitability for use in future sarbecovirus-origin epidemics or pandemics.