The Gamelaya Research Institute, part of Russia’s Health Ministry launched clinical trials of the vaccine, Gam-Covid-Vac (later renamed – Sputnik V) at two hospitals in Russia in June. There was a significant concern in the safety and efficacy of the vaccine when the Russian President announced that the vaccine was approved and claimed it to be the first registered COVID-19 vaccine, even before the phase-3 trials.

According to the preliminary results published in the Lancet, the vaccine has been shown to produce an antibody response in all 76 participants in the early-stage trials.

Sputnik V is a viral vector type of vaccine, where weakened forms of human adenoviruses (viruses that cause the common cold) are genetically modified to carry the gene for SARS CoV-2 spike glycoprotein to trigger an immune response in the body. It uses two different strains of human adenoviruses, a recombinant adenovirus type 26 (rAd26) vector and a recombinant adenovirus type 5 (rAd5) vector for the first and second vaccination dose, to boost the effectiveness of the vaccine.

The vaccine was designed in two formulations, frozen (Gam-COVID-Vac) and lyophilized or freeze-dried (Gam-COVID-Vac-Lyo). The lyophilized form was developed for vaccine delivery to hard-to-reach regions as it can be stored at 2-8 degrees celsius and the frozen form (can be stored at -18 degree celsius) was developed for large-scale use.

Phase 1 and 2 trials for this vaccine which took place in two hospitals in Russia involved healthy adults aged 18-60 years. In phase 1 of each trial, participants were administered intramuscularly with one component of the two-part vaccine – four groups of nine participants were given the frozen or lyophilized rAd26-S or rAd5-S component. The safety of the vaccine was assessed for 28 days.

In phase 2, which began no earlier than five days after the phase 1 trial began, 20 participants each in the frozen and lyophilized vaccine groups were administered intramuscularly with the full two-part vaccine – they received a prime vaccination with the rAd26-S component on day 0, followed by a booster vaccination with rAd5-S component on day 21.

According to the study, both vaccine formulations were safe over the 42-day study period and well-tolerated. The study also mentioned that antibody levels against the spike protein in those who received vaccination were comparable to SARS-CoV-2 antibodies in Russian patients who had been naturally infected with COVID-19 and recovered. The most common adverse events were pain at the injection site, hyperthermia, headache, asthenia (weakness or lack of energy), and muscle and joint pain. The study noted that these adverse effects are also seen with other vaccines, particularly viral-vector-based ones, and no serious adverse events were reported during the study.

However, the study also noted that further investigation is needed to establish the effectiveness of the vaccine to prevent COVID-19 infection. Phase 3 trials of the vaccine are currently underway in Russia and UAE. In India, the DCGI has finally approved Dr. Reddy’s to conduct phase 2/3 trials for the vaccine.