We report the direct comparison of monomeric, dimeric and trimeric RBD protein subunit vaccines to a virus-like particle (VLP) displaying RBD. After two and three doses, a RBD dimer and trimer elicited antibody levels in mice comparable to an RBD-VLP. Furthermore, an Omicron (BA.1) RBD hetero-dimer induced neutralizing activity similar to the RBD-VLP. A RBD hetero-dimer and RBD-VLP also shows comparable breadth to other SARS-CoV-2 variants-of-concern (VOCs).