Russia’s controversial COVID-19 vaccine showed signs of producing an immune response in an early test, according to a report published in the Lancet on 4 September.
The report includes the details from two early phase 1/2 studies of the vaccine, Sputnik V, at two hospitals in Russia.
Researchers enrolled 76 participants in the two studies, 38 in each study, between June and August. Participants were aged between 18 and 60 years and were monitored for 42 days following initial dosing with the vaccine candidate.
During this closely-monitored period, the researchers said that all participants given the vaccine developed antibodies against the SARS-CoV-2 virus, which causes COVID-19, within three weeks.
Although some side effects were reported, with the most common including pain at the injection site and fever, the vaccine proved safe and well tolerated.
Sputnik V consists of two strains of adenoviruses, which usually cause the common cold, to carry the gene for the SARS-CoV-2 spike protein.
This method is similar to that being used by AstraZeneca and Oxford University, whose vaccine candidate uses a modified chimpanzee adenovirus.
A large-scale phase 3 trials is planned to enrol 40,000 volunteers from different age and risk groups, with initial results from this study expected in October or November.
Despite the lack of robust evidence from a large confirmatory study, Russia granted regulatory approval for Sputnik V in August.
There was a widespread reaction across the globe, with health experts warning that the approval should not have pre-empted the completion of phase 3 testing.
Following the Lancet report, scientists have said that although the early results are promising, it is important to remember that there is too little data to definitively confirm efficacy.
“The immunogenicity bodes well, although nothing can be inferred on immunogenicity in older age groups, and clinical efficacy for any COVID-19 vaccine has not yet been shown,” said Naor Bar-Zeev, assistant professor at Johns Hopkins Bloomberg School of Public Health.
“Since vaccines are given to healthy people and, during the COVID-19 pandemic, potentially to everyone after approval following phase 3 trials, safety is paramount,” he added.
Russian President Vladimir Putin said last month that one of his daughters had volunteered to receive the vaccine, adding that “she’s feeling well and has a high number of antibodies” after receiving the shot.
Sputnik V was developed by Moscow’s Gamaleya Institute, which faced criticism after researchers and directors injected themselves with the prototype months ago, bypassing the usual process of initiating human trials.