Russia on Wednesday started inoculating volunteers with the “Sputnik V” vaccine against the coronavirus in Moscow, AFP reported. “The first participants have already had the vaccination at clinics in the capital,” Moscow Deputy Mayor Anastasia Rakova said.

This came as 26 scientists issued an open letter to medical journal The Lancet, raising questions on the accuracy of data from the vaccine’s early-stage trials, saying it looked “highly unlikely”, Reuters reported.

The signatories of the letter said that data from phase 2 and 3 trials of “Sputnik V” showed that several participants had the same level of antibodies in their system. “On the ground of simple probabilistic evaluations, the fact of observing so many data points preserved among different experiments is highly unlikely,” the signatories said. The letter, which is in Italian, was posted by a scientist named Enrico Bucci on Facebook.

The scientists clarified that their conclusion was based on the summary of the study published in the medical journal and not the original data. “In lack of the original numerical data, no conclusions can be definitively drawn on the reliability of the data presented, especially regarding the apparent duplications detected,” they said.

The concerns raised by the open letter have been rejected by the Gamaleya Institute that created the vaccine. “The published results are authentic and accurate and were examined by five reviewers at The Lancet,” Denis Logunov, a deputy director at the institute said.

The Lancet, on the other hand, asked the authors of the vaccine study to answer the questions raised by the signatories, TASS reported. “The Lancet has invited the authors of the Russian vaccine study to respond to the questions raised in the open letter by Enrico Bucci [a biology professor at Temple University in Philadelphia, Pennsylvania],” the medical journal said. “We continue to follow the situation closely.”

They added: “We encourage scientific debate on papers we have published, and are aware of the open letter on the Russia vaccine trial by Logunov et al. We have shared the letter directly with the authors and encouraged them to engage in the scientific discussion.”

Russia had rolled out the first batch of the vaccines for public use on Tuesday. The vaccine was found to produce an antibody response in all participants in early-stage trials, according to results published in medical journal The Lancet on Friday.

Russia, which on August 11 announced that it has developed the world’s first coronavirus vaccine, had been criticised by scientists and experts for not conducting Phase 3 trials to determine its safety. A vaccine is deemed safe to be commercially available only after Phase 3 – a much larger efficacy trial involving thousands of participants. The advanced trial for the vaccine began on August 26. Russian Healthcare Minister Mikhail Murashko said on Wednesday that about 31,000 volunteers out of planned 40,000 have already been selected for the clinical trials, according to TASS.

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