MOSCOW, October 28. /TASS/. Russian medics have tracked the impact of vaccination with Sputnik Light and discovered that the strongest immune reaction appeared in those who have previously had COVID-19. The results of their observations were published in an article posted on the medRxiv electronic scientific library.
"Our results showed that vaccination with Sputnik Light in cases of individuals previously exposed to the virus considerably boosts the existing immune response against the virus. In these individuals, RBD-specific IgG titers, S-protein-specific T cells, and VNA in serum were already elevated on the 7th day after vaccination, in contrast to the COVID-19-naive individuals, who developed the antibody response and VNA in serum mainly 21 days post-vaccination," the scientists wrote.
The emergence of the coronavirus Delta strain and its other new variants led to worry that new versions of the virus may soon appear which will be resistant to vaccines and antibodies. This made the authorities of many countries think about conducting national revaccination campaigns the efficacy of which remains to be seen.
A group of Russian medics led by Elena Vasilieva of the Davydovsky State Clinical Hospital in Moscow has obtained the first results of this kind for the Sputnik Light vaccine which is already being used for initial inoculation and revaccination in Russia.
Vaccine’s high efficacy
Some 84 volunteers participated in the study who previously had not been inoculated with any vaccines against coronavirus used nowadays in Russia. Half of them have already had COVID-19 in various forms, therefore they developed antibodies to SARS-CoV-2.
The scientists decided to use this opportunity to evaluate the efficacy of Sputnik Light for revaccination. In order to do so, they inoculated all the study participants and during the following three weeks periodically tested their blood, evaluating the concentration of antibodies and their activity while interacting with the particles of the Alpha and Delta variants of SARS-CoV-2.
As these observations demonstrated, inoculation led to the formation of antibodies to the coronavirus in both groups of volunteers, but Sputnik Light worked significantly faster and stronger in those who have had the virus before. For instance, the concentration peak of antibodies was reached as early as one week following inoculation while their activity against the Delta variant was noticeably higher than in those who have not had the virus earlier.
According to the scientists, this testifies to the possible application of Sputnik Light both for initial inoculation and revaccination, capable of a high degree of protection against the Alpha and Delta strains of SARS-CoV-2.