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Covid-19 Vaccine Shown Safe, Effective in Russian Test

Red Square, Moscow

Red Square, Moscow (A. Kotok)

2 Feb. 2021. Interim results from a clinical trial in Russia of a two-dose vaccine show a high efficacy rate in preventing Covid-19 disease and few serious adverse effects. Findings from the trial of the Gam-COVID-Vac vaccine candidate, brand-named Sputnik V, developed by the Gamaleya National Center of Epidemiology and Microbiology in Moscow, appear in today’s issue the journal The Lancet.

The Gam-COVID-Vac vaccine is made of SARS-CoV-2 viral particles delivered in engineered adenoviruses, benign viruses now widely used to deliver gene and cell therapies. The vaccine is given in two injections, 21 days apart. The study team says the vaccine and placebo used in the trial are produced according to international Good Manufacturing Practices for pharmaceuticals. And the researchers, led by project director Alexander Gintsburg, say early and mid-stage trial results show the vaccine induces an immune response with antibodies and T-cells, and a favorable safety profile.

The late-stage clinical trial enrolled 35,963 participants at 25 hospitals and clinics in Moscow, from September through November 2020. Of that original pool, nearly 14,000 did not meet eligibility requirements, leaving 21,977 participants for the study. Participants were randomly assigned on a three-to-one ratio to receive Gam-COVID-Vac or a placebo, in two doses, 21 days apart. The demographics show participants are largely male (61%), and almost entirely White (99%)

Participants are then tracked for six months, with the study team looking primarily for evidence of Covid-19 disease, confirmed with RT-PCR diagnostic tests. Researchers are also taking blood tests from subsets of participants to measure antibody concentrations, and gauging disease severity and adverse effects.

Similar efficacy rates across age groups

The results show, after 21 days following the second dose, 78 participants in the trial contracted Covid-19 disease, of which 62 were placebo recipients (1.3%) and 14 among Gam-COVID-Vac recipients (0.1%). Those findings translate to an efficacy rate of 92 percent. Efficacy rates for participants age 50 and over are similar, 92 or 93 percent, to the total sample rate. In addition, blood samples from participants show Gam-COVID-Vac recipients with higher concentrations of neutralizing antibodies and more IFNy cytokines, enzymes indicating T-cell activity, than placebo recipients.

The researchers say the most common adverse effects are flu-like illness, injection site reactions, headache, and overall weakness. Serious adverse effects were recorded in 45 vaccine recipients (0.3%) and 23 placebo recipients (0.4%). None of the serious adverse effects, say the researchers, are attributed to the vaccine, and confirmed by an independent data monitoring committee. Likewise, four deaths that occurred in the trial, three among vaccine recipients and one in the placebo group, were not due to the vaccine.

The authors acknowledge the short time interval following the second dose prevents an indication of the durability of the Gam-COVID-Vac vaccine’s efficacy. With the sample almost exclusively White, the results also provide little guidance for other races and ethnic groups. And the results do not show the efficacy of the vaccine against any of the recently emerging variants from the U.K., South Africa, and Brazil.

The Russian government already authorized the Gam-COVID-Vac vaccine for populations considered at higher risk of Covid-19 disease, including medical workers and teachers. Trials of the vaccine are also underway in other parts of Russia, Belarus, United Arab Emirates, and India. And a separate trial is underway testing a single dose of the Gam-COVID-Vac vaccine.

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