By Polina Ivanova and Polina Nikolskaya
MOSCOW (Reuters) – 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.
This, he said, confirmed the memory cells were working.
“It was not necessary for them to be revaccinated,” Gintsburg told Izvestia.
Some scientists have voiced concerns that people could become resistant to the vaccine after the first two shots, with their bodies generating immunity to the so-called viral vector, which relays genetic information, on which the vaccine is based. This had not been the case in the early revaccinations, lead vaccine developer Denis Logunov said.
Sputnik V vaccinations are widely available and offered without charge and regardless of age in Russia, including on a drop-in basis in vaccine centres set up in shopping malls.
A database is maintained but some people have managed to get round the guidelines by having more than two shots.
A group set up on the Telegram messenger app to discuss third and fourth shots has collected over 20 cases of revaccination, according to the forum’s hosts.
The health ministry, which also oversees the Gamaleya Institute, did not comment.
The chief executive of a big company and a manager at a state bank told Reuters they had each received another shot after having the initial two doses, having been told by scientists it was safe to do so.
Moscow resident Kirill, 47, told Reuters he had his first shot and booster last autumn during vaccine trials. After buying an antibody test, he discovered in February that his antibody levels had halved.
Worried about having to look after relatives with COVID-19, he had third and fourth shots in a mall where he said no-one looked at the vaccination database.
“My number of antibodies shot up (afterwards),” he said.
Kirill Dmitriev, head of the Russian Direct Investment Fund, the sovereign wealth fund responsible for marketing Sputnik V abroad, got revaccinated when his antibody levels fell, over eight months after having his first two shots during trials. He said he wanted to check how well his memory cells were working.
“After three days, my antibody levels zoomed up,” he told Reuters. “I need not have been revaccinated.”
(Additonal reporting by Tatiana Voronova and Olesya Astakhova; Writing by Polina Ivanova; Editing by Timothy Heritage)