Last month President Vladimir Putin ordered a review of Russian-produced vaccines for their effectiveness against new variants spreading in different parts of the world.
“A recent study carried out by the Gamaleya Centre in Russia showed that revaccination with Sputnik V vaccine is working very well against new coronavirus mutations, including the UK and South African strains of coronavirus,” said Denis Logunov, a deputy director of the centre, which developed the Sputnik V shot.
Results of the trial are expected to be published soon, but this was the first indication of how the tests are going. No further details were available yet.
So-called viral vector shots - such as Sputnik V and a shot developed by AstraZeneca - use harmless modified viruses as vehicles, or vectors, to carry genetic information that helps the body build immunity against future infections.
The revaccination used the same Sputnik V shot, based upon the same adenovirus vectors. The trial indicated this did not impact effectiveness, Logunov said.
Some scientists have raised the possible risk that the body also develops immunity to the vector itself, recognising it as an intruder and trying to destroy it.
But developers of Sputnik V disagreed this would pose long-term problems.
“We believe that vector-based vaccines are actually better for future revaccinations than vaccines based on other platforms,” Logunov said.
He said that the researchers found that antibodies specific to the vectors used by the shot - which could generate an anti-vector reaction and undermine the work of the shot itself - waned “as early as 56 days after vaccination”.