Russian scientists say the country's Sputnik V vaccine appears safe and effective against Covid-19, according to early results of an advanced study published in a British medical journal.
The news is a boost for the shot that is increasingly being purchased by nations around the world who are desperate to stop the devastation caused by the pandemic.
Researchers say based on their trial, which involved about 20,000 people in Russia last fall, the vaccine is about 91 per cent effective and that the shot also appeared to prevent people from becoming severely ill with Covid-19. The study was published online Tuesday in the journal, Lancet.
Scientists not linked to the research acknowledged that the speed at which the Russia vaccine was made and rolled out was criticized for “unseemly haste, corner cutting and an absence of transparency.”
“But the outcome reported here is clear,” British scientists Ian Jones and Polly Roy wrote in an accompanying commentary. “Another vaccine can now join the fight to reduce the incidence of Covid-19.”
The Sputnik V vaccine was approved by the Russian government with much fanfare on August 11. President Vladimir Putin personally broke the news on national television and said that one of his daughters had already been vaccinated with it. At the time, the vaccine had only been tested in several dozens of people.
Some early results were published in September, but participants had only been followed for about 42 days and there was no comparison group.
The latest study is based on research involving about 20,000 people over age 18 at 25 hospitals in Moscow between September and November, of whom three-quarters got two doses of the Russian vaccine 21 days apart and the remainder got placebo shots.
The most commonly reported side effects were flu-like symptoms, pain at the injection site and fatigue. Serious side effects were rare in both groups and four deaths were reported in the study, although none were considered to be the result of the vaccine.
The study included more than 2,100 people over age 60 and the vaccine appeared to be about 92 per cent effective in them. The research is ongoing but in December, Russia's Health Ministry said it would cut the size of the study from the expected 40,000 to about 31,000 volunteers that have already enrolled. Developers of the vaccine cited ethical concerns about using placebo shots.
The Russian vaccine uses a modified version of the common cold-causing adenovirus to carry genes for the spike protein in the coronavirus as a way to prime the body to react if Covid-19 comes along. That's a similar technology to the vaccine developed by AstraZeneca and Oxford University. But unlike that two-dose vaccine, the Russians used a slightly different adenovirus for the second booster shot.
Some experts say that approach may explain why the Russian vaccine seems to have produced a better immune response than the AstraZeneca vaccine, which has a reported efficacy rate of about 60 to 70 per cent.
“This aims to drive higher immune responses to the target 'spike' by using two slightly different jabs,” said Alexander Edwards, an associate professor in biomedical technology at Britain's University of Reading.
He said if you have two identical shots, it's possible the immune system doesn't get as big a boost from the second injection.
He added that, because the Russian vaccine is made using a tested technology, it should be possible to scale up manufacturing.