(CNN) – After criticism last year for an early launch, Russia’s Sputnik V coronavirus vaccine is 91.6% effective in preventing symptomatic covid-19 and 100% effective in preventing serious disease, according to an interim analysis by Phase 3 data study published in the medical journal The Lancet on Tuesday.
The randomized, double-blind, placebo-controlled clinical trial includes data from 19,866 participants (14,964 received the vaccine and 4,902 received the placebo). There were 78 cases of Covid-19 among the trial participants and only 16 of them had received the vaccine. The rest were given a placebo, which does nothing.
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The study included 2,144 people over 60 years of age and a sub-analysis conducted in this group showed that the vaccine was well tolerated and had a comparable efficacy of 91.8%.
The analysis includes only symptomatic COVID-19 cases, and the authors note that more research is needed to understand the efficacy of the asymptomatic COVID-19 vaccine, transmission, and duration of protection.
Seventy serious adverse reactions were reported in 68 subjects, including 45 in the vaccine group and 23 in the placebo group, but none were considered associated with vaccination, according to the study. Most of the side effects reported were mild, such as flu-like symptoms and injection site pain.
The Russian Sputnik vaccine is a two-dose adenoviral vector, with doses given 21 days apart. In this type of vaccine, the adenovirus is altered so that it can deliver a piece of genetic material from another pathogen, such as the virus that causes covid-19. It is a similar approach to the vaccines developed by AstraZeneca and Johnson & Johnson.
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Sputnik V uses two different vectors based on human adenoviruses in separate injections. Researchers at the Gamaleya National Research Center for Epidemiology and Microbiology in Russia write that using a different adenovirus vector for a booster can create a more potent immune response than using the same vector a second time, by minimizing the risk of immune system resistance.
Sputnik V only needs to be refrigerated and costs $ 10 per dose, according to Russia’s Direct Investment Fund, which funded vaccine production and is responsible for its worldwide sales.
The vaccine has already been approved in Russia, Belarus, Serbia, Argentina, Bolivia, Algeria, Palestine, Venezuela, Paraguay, Turkmenistan, Hungary, the United Arab Emirates, Iran, Guinea, Tunisia and Armenia. To date, Sputnik V has been administered to more than 2 million people around the world.