MOSCOW (AP) – Russia’s health ministry agreed on Wednesday to reduce the size of a nationally developed coronavirus vaccine study and stop enrolling volunteers.
The decision comes a week after developers said enrollment of study volunteers has been declining since Russia began administering the Sputnik V vaccine while the final-stage study was still ongoing. They also cited ethical concerns about giving a fictitious shot to some of the volunteers. The size of the study was reduced to approximately 31,000 from 40,000 participants.
Alexander Gintsburg, head of the Gamaleya Center, the state medical research institute that developed Sputnik V, said many of those who received fake shots had discovered it and been vaccinated.
If they drop a large number of volunteers from the placebo group, this could affect the results, said Svetlana Zavidova, executive director of the Association of Clinical Trials Organizations of Russia.
“They just won’t be able to gather (the necessary statistics),” he said.
Russia has been widely criticized for passing Sputnik V regulations in August after the vaccine was only tested on a few dozen people. Two weeks later, the study of 40,000 volunteers was announced.
Despite warnings awaiting the results of the study, Russian authorities began offering it to people at risk groups (such as medical workers and teachers) within weeks of approval.
President Vladimir Putin, who has publicly acclaimed Sputnik V, ordered the Russian government this month to launch a large-scale vaccination campaign. By mid-December, more than 150,000 people had been vaccinated, according to Gintsburg.
In a statement, the Ministry of Health said data from the interim study on vaccine safety and efficacy were considered part of the decision to reduce the size of the study. The ministry said the study would continue and that participants would be monitored for at least another six months.
Gintsburg had suggested administering the vaccine to all volunteers who received the placebo placebo, but the ministry said there would be no “outcome” of the study at this time. In other words, volunteers will not be told if they received real or fake vaccines.
Kirill Dmitriev, head of Russia’s Direct Investment Fund, which funded Sputnik V, noted that recently U.S. drug maker Johnson & Johnson reduced the size of its vaccine trial.
The developers of Sputnik V have said that the data suggest that the vaccine was 91% effective, a finding based on 78 coronavirus infections among nearly 23,000 participants. There are far fewer cases that Western drug manufacturers have accumulated during the final tests before analyzing the performance of their candidate. Important demographic and other data from the study have also not been released.
Western vaccine developers have released much more information, although much is still unknown about the Russian vaccine, said Ilya Yasny, head of scientific research at Russian investment fund Inbio Ventures.
“We don’t have data on the proven effectiveness of the vaccine other than what Gintsburg and the Russian Direct Investment Fund say,” Yasny said.