One or two dose regimen of the SARS-CoV-2 synthetic DNA vaccine INO-4800 protects against respiratory tract disease burden in nonhuman primate challenge model

Safe and effective vaccines will provide essential medical countermeasures to tackle the COVID-19 pandemic. Here, we assessed the safety, immunogenicity and efficacy of the intradermal delivery of INO4800, a synthetic DNA vaccine candidate encoding the SARS-CoV-2 spike protein in the rhesus macaque model. Single and 2 dose vaccination regimens were evaluated. Vaccination induced both binding and neutralizing antibodies, along with IFN-gamma-producing T cells against SARS-CoV-2. Upon administration of a high viral dose (5 x 10(6) pfu) via the intranasal and intratracheal routes we observed significantly reduced virus load in the lung and throat, in the vaccinated animals compared to controls. 2 doses of INO-4800 was associated with more robust vaccine-induced immune responses and improved viral protection. Importantly, histopathological examination of lung tissue provided no indication of vaccineenhanced disease following SARS-CoV-2 challenge in INO-4800 immunized animals. This vaccine candidate is currently under clinical evaluation as a 2 dose regimen. Crown Copyright (C) 2021 Published by Elsevier Ltd.

Automated summary

The study assessed the safety, immunogenicity, and efficacy of a synthetic DNA vaccine candidate in rhesus macaques, finding that a two-dose regimen induced stronger immune responses and improved viral protection. Histopathological examination showed no evidence of vaccine-enhanced disease in vaccinated animals after challenge with SARS-CoV-2.