ABSTRACT
Safe and effective vaccines will provide essential medical countermeasures to tackle the COVID-19 pandemic. Here, we evaluate the safety, immunogenicity and efficacy of the intradermal delivery of INO-4800, 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 induces both binding and neutralizing antibodies, along with IFN-γ-producing T cells against SARS-CoV-2. Upon administration of a high viral dose (5 x 106 pfu) via the intranasal and intratracheal routes we observe significantly reduced virus load in the lung and throat, in the vaccinated animals compared to controls. 2 doses of INO-4800 is associated with more robust vaccine-induced immune responses and improved viral protection. Importantly, histopathological examination of lung tissue provides no indication of vaccine-enhanced disease following SARS-CoV-2 challenge in INO-4800 immunized animals. This vaccine candidate is currently under clinical evaluation as a 2 dose regimen.