The results, published on bioRxiv, demonstrated that INO-4800 reduced viral load in the lungs and nasal passages of macaques that received two doses of INO-4800 (one mg) four weeks apart followed by live virus challenge 13 weeks after the second dose.

The vaccinated macaques demonstrated seroconversion after a single dose, with neutralizing antibodies and T cells found in their blood more than four months after the initial dose. Moreover, the levels of antibodies were similar to or greater than those who have recovered from COVID-19. The study showed that the vaccine induced acute and memory T- and B-cell responses, including neutralizing antibodies against the early virus strain as well as the now dominant G614 variant.

The company anticipates beginning phase II/III efficacy trials this summer. A separate nonhuman primate study evaluating the durability of INO-4800 at 12 months postvaccination is currently underway and is supported by the federal government's Operation Warp Speed to accelerate development of a vaccine for SARS-CoV-2.