This study develops a lipid nanoparticle (LNP)-based DNA vaccine to protect against SARS-CoV-2 variants of concern (VOCs). The researchers screened a library of LNPs encapsulating unique barcoded DNA (b-DNA) to identify the most effective LNPs for DNA delivery in lymphoid tissues. The top-performing LNP, LNP-HPS, was then used to encapsulate plasmid DNA encoding the HexaPro version of the SARS-CoV-2 spike protein. In preclinical models, LNP-HPS elicited robust protective effects against the SARS-CoV-2 Gamma (P.1) variant, reducing lethality, viral load in the lungs, and lung damage. LNP-HPS also induced potent humoral and T cell responses, generating high levels of neutralizing antibodies against both P.1 and the Omicron (B.1.1.529) variants. The protective efficacy and immunogenicity of LNP-HPS were comparable to those achieved by the approved COVID-19 vaccine from Biontech/Pfizer. These findings suggest that LNP-HPS holds great promise as a vaccine candidate against VOCs.This study develops a lipid nanoparticle (LNP)-based DNA vaccine to protect against SARS-CoV-2 variants of concern (VOCs). The researchers screened a library of LNPs encapsulating unique barcoded DNA (b-DNA) to identify the most effective LNPs for DNA delivery in lymphoid tissues. The top-performing LNP, LNP-HPS, was then used to encapsulate plasmid DNA encoding the HexaPro version of the SARS-CoV-2 spike protein. In preclinical models, LNP-HPS elicited robust protective effects against the SARS-CoV-2 Gamma (P.1) variant, reducing lethality, viral load in the lungs, and lung damage. LNP-HPS also induced potent humoral and T cell responses, generating high levels of neutralizing antibodies against both P.1 and the Omicron (B.1.1.529) variants. The protective efficacy and immunogenicity of LNP-HPS were comparable to those achieved by the approved COVID-19 vaccine from Biontech/Pfizer. These findings suggest that LNP-HPS holds great promise as a vaccine candidate against VOCs.