MOSCOW: Some Russians who have taken Covid-19 antibody tests and found their antibodies have fallen are having third and fourth shots of the Sputnik V vaccine, but researchers in the country suggest they are unnecessary.
Revaccination in effect simulates getting the disease so that the body develops more antibodies to fight it. Researchers have said an immediate rise in antibodies seen by those getting a third or fourth shot suggests they did not need revaccination.
Sputnik V was one of the first vaccines widely used in a population, so Russia’s findings on revaccination will be closely watched elsewhere. The question of how long a vaccine offers protection against Covid-19 will be vital as countries gauge when or whether revaccination will be needed.
Russia has since its January roll-out been giving its citizens two shots of Sputnik V, with the booster following 21 days after the initial dose. Antibody tests are widely available in clinics in big cities.
Scientists at Moscow’s Gamaleya Institute, which developed the vaccine, say a fall in antibody levels does not indicate a decline in immunity or that revaccination is needed.
The number of antibodies in the blood is not the only indicator of protection, they say, and memory cells continue to defend the body against Covid-19 for much longer.
The number of people known to have had a third or fourth vaccination is small, as many are side-stepping government policy to get extra shots. Research into their impact is limited.
But Alexander Gintsburg, the director of the Gamaleya Institute, said results from initial, ad hoc experiments showed memory cells were working and Gamaleya scientists expect immunity provided by Sputnik V to last at least two years.
Gintsburg told Izvestia newspaper that some Gamaleya Institute staff members got revaccinated around 12 months after their first doses, and their antibody levels soared within days. - Reuters