The EU drug regulator is unlikely to decide whether to approve Russia's Sputnik V coronavirus vaccine until at least the first quarter of 2022 because some data needed for the review is still missing, a source with knowledge of the matter said.
"An EMA decision by the end of the year is now absolutely impossible," the source said, referring to the European Medicines Agency.
If the required data is received by the end of November, "then the regulators may well decide in the first quarter of next year", he said. He declined to be identified due to the sensitivity of the matter.
The EMA, which launched its formal review of the Russian vaccine in March, had previously been expected to decide in May or June whether to approve use of the vaccine in the bloc.
The results of Phase III trials published in The Lancet in February have shown it is almost 92% effective. Russia said later Sputnik V is around 83% effective against the Delta variant.
The vaccine is widely used in Russia and approved for use in more than 70 countries. The source said there was no reason to doubt its effectiveness or safety.
Gamaleya Institute, which is supervised by Russia's health ministry, developed the vaccine and oversaw the clinical trials, while Russia's sovereign wealth fund, the Russian Direct Investment Fund (RDIF), markets Sputnik V overseas.
RDIF declined to comment and the health ministry did not respond to requests for comment.
The EMA said in an email the vaccine remains under rolling review until sufficient evidence is available for a formal marketing authorisation application.
"EMA will be in a better position to comment on possible timelines for an authorisation of Sputnik V once a marketing authorisation application has been submitted to the agency," it said.
It said on Sept. 9 it was awaiting more data on Sputnik V before it could progress its review.
"EMA asked for a more complete dossier on production, details of how the vaccine is produced. When they have this dossier they will also be able to understand where to ask for inspections," the source said.
These details concerned both the production of the active ingredient and the bottling of the finished product, the source said.
The slow pace of approval is the latest blow for Moscow, which hopes the backing of an international regulator will allow it to compete with vaccines made by U.S. drugmakers Pfizer and Moderna which have become dominant on the global market.
Manufacturers have told Reuters that they have had difficulties producing the second dose of the vaccine, hampering efforts to boost output at home.
EU approval would also be a major relief for Russians wanting to travel to the region as it only recognises vaccines authorised by the EMA or the World Health Organization.
The WHO's review as part of the process for including the shot in its programme for supplying poorer countries has also encountered hitches.
Reuters reported in July that the developers of Sputnik V had repeatedly failed to provide data that regulators deem to be standard requirements in the approval process.
A second source involved in the manufacturing process told Reuters the review was slow because Gamaleya did not have experience of dealing with an international drug regulator.
The first source said the developers had also changed the production sites of the vaccine doses for the EU a few times, a further reason for delays.
"They keep changing the location of the vaccine production sites that are supposedly destined for Europe," he said.
The EMA reviews each facility involved in the production process. The chairman of Russian drugmaker R-Pharm Alexey Repik said its factories would be included in the application to the EMA, but he did not provide further details.
A third source involved in producing the shot in Russia said the EMA inspectors had visited at least two sites operated by R-Pharm in the western Yaroslavl region. EMA had no critical remarks about these sites, he said.
A third R-Pharm site in Moscow would also produce shots for the EU, but it was included in the regulatory submission after the EMA's review started, he said.
Inspection was expected before year-end, he said.
The EU ambassador to Moscow said on Oct. 8 Russia had repeatedly delayed inspections by the EMA necessary for the certification of its vaccine.
The first source with knowledge of the matter said there was no reason to doubt that Sputnik was safe and effective.
"But with this incomplete data, the EMA doesn't really have the material on which to make a judgement," he said.
"The ball is in their court. They have to decide what they want to do."