Interim results from the phase I trial demonstrated that the vaccine was well tolerated and no significant safety concerns were noted to date   .
Updated data from a phase I trial demonstrated that antibody responses by ELISA in 94% of subjects at week 14 (two weeks post-third dose). Also, broad-based t cell responses were observed in 88% of participants. No statistically significant dose-dependent differences in antibody response rates (91%, 95%, and 95% at doses of 0.67, 2, and 6 mg, respectively) were reported. Durable antibody responses to the vaccine were also maintained through 60 weeks following dosing. Earlier results demonstrated that after a three dose vaccine regimen with GLS 5300 intramuscular, high levels of binding antibodies were measured in 92% (57 of 62) of evaluated subjects. Earlier reported interim results showed that single or two doses of the vaccine generated a robust antibody response in 84% or 44% of evaluated participants, respectively. Significant antigen-specific cytotoxic T-lymphocyte (CTL) responses were observed and 98% of subjects generated an antibody and/or T cell response against the MERS vaccine. Results were presented from the 75 healthy volunteers      .
A DNA vaccine construct targeting multiple Middle Eastern respiratory syndrome (MERS) coronavirus antigens was immunogenic and seroconversion was observed in mice. The antibodies generated in 100% of the mice (n = 20) were able neutralise the MERS virus infection; unvaccinated mice (n = 10) did not produce neutralising antibodies. The vaccine also elicited a robust and broad T cell response in mice, producing CD8+ and CD4+ T cells responses against multiple epitopes of the MERS spike protein  .
The DNA-based MERS vaccine when administered in mice, camels and monkeys, induced a robust immune response capable of preventing the virus from infecting cells  .