An experimental coronavirus drug produced by Inovio Pharmaceuticals Inc has shown promising results, and in an early-stage human trial, was found to be safe, the company disclosed on Tuesday.

The vaccine, one of 17 being trialed in humans and part of Operation Warp Speed initiative of the Trump administration, triggered immune responses in 34 out of 36 healthy subjects aged 18 to 50 years, Inovio stated.

Nevertheless, the biotech firm did not provide further information on the exact reaction caused by the vaccine, saying that the full data would later be released in a peer-reviewed scientific journal.

Given to 40 patients, the vaccine caused an immune system response in 94 percent of individuals who completed the Phase One clinical test, which means they were given two shots, four weeks apart.

Called INO-4800, Inovio's experimental drug is developed to inject DNA into a patient to trigger a particular response against the SARS-CoV-2 virus.

The vaccine is administered using a needle under the patient's skin, then activated with a device resembling a toothbrush which provides an electrical impulse for a fraction of a second allowing the DNA to penetrate the cells of the body and perform its mission.

Immune responses in the research were strictly monitored and gauged by the potential drug's capacity to create binding antibodies, or virus-neutralizing antibodies and T-cell reactors, two criteria viewed as critical for a successful medication.

Shares of Inovio stock, which have climbed in market value earlier this year, settled down nearly 15 percent, to $26.95, during Tuesday's session as Wall Street analysts stated the preliminary figures provided only limited information into the vaccine's actual effectiveness.

The American biotech group based in Plymouth Meeting, Pennsylvania has been considered as a leading candidate in the scramble to produce medication for COVID-19. However, its technology platform, based on synthetic DNA, has yet to produce an approved vaccine. The system was pioneered three decades ago by David Weiner, who co-founded the group and is now a scientific adviser.

More research would be required to prove if the antibody and other responses signify that the vaccine can contain the disease in humans. Inovio disclosed that it plans to start mid-to-late phase research in the summer to evaluate the drug's rate of safety and efficacy.

According to Inovio chief executive officer Joseph Kim, Inovio's vaccine is the only DNA drug that is stable at room temperature for over a year and does not require refrigeration for storage for many years, which is a major advantage in terms of vaccinating patients in developing countries.