The backer of Russia's Sputnik V vaccine has demanded that Slovakia return thousands of doses after the country's drug regulator said the doses received differed from those being reviewed by the European Union's drug overseer.
The back-and-forth between Bratislava and Moscow on April 8 added further confusion to the ongoing effort to get the Russian vaccine distributed and into people's arms across Europe.
Slovakia, along with Hungary, turned to the Russian vaccine even though it has not been cleared by the European Medicines Agency (EMA). Several other EU member states are actively considering it.
Slovakia, which received 200,000 batches of Sputnik V last month, has recorded more than 368,000 coronavirus cases and nearly 10,300 COVID-19-related deaths, according to Johns Hopkins University.
The Slovak State Institute for Drug Control said on April 7 that there were lingering questions about the efficacy and risks of the Russian vaccine, due mainly to inadequate data from the producer, and that was preventing doses from being rolled out across the country.
On April 8, the institute also said the Sputnik V doses it was examining were not the same as those being reviewed by the EMA, or apparently those that were reviewed in the British medical journal The Lancet.
"Batches of the vaccine used in preclinical tests and clinical studies published in The Lancet journal do not have the same characteristics and properties as batches of vaccine imported to Slovakia," it said a statement.
RFE/RL's Coronavirus Coverage
Features and analysis, videos, and infographics explore how the COVID-19 pandemic is affecting the countries in our region.
Reuters earlier quoted the institute as saying that an official report was sent to Moscow on March 30, in which the regulator cited "an amount of missing data from the producer, inconsistency of dosage forms, and [the] impossibility of mutually comparing batches used in various studies and countries."
Later on April 8, the Russia Direct Investment Fund (RDIF), the sovereign wealth fund that has been the primary promoter of Sputnik V outside of Russia, said it had asked Slovakia to return the doses.
The fund also requested that a batch be sent to a specially certified laboratory for further checks, and in a series of posts to the vaccine's official Twitter account, it accused the Slovak institute of "an act of sabotage" and a "disinformation campaign."
"Unfortunately, in violation of existing contract and in an act of sabotage the State Institute of Drug Control ensured that Sputnik V was tested" at an unauthorized laboratory, the vaccine backers said in one post.
RDIF chief Kirill Dmitriyev, meanwhile, met in Moscow with Slovak Deputy Prime Minister Igor Matovic, who last week was forced to step down as prime minister amid reports of a secret deal to procure 2 million doses of the Russian vaccine.
Afterward, Matovic blasted his opponents in Slovakia on his official Facebook page.
"CONGRATULATIONS, YOU IDIOTS! You have taken the health of millions of people in Slovakia hostage!" he wrote.
The EMA is reviewing data from Russia before it decides whether to authorize the vaccine's use in the EU. The agency has raised questions about possible ethical problems during Sputnik V's clinical trials.
Russian backers of the vaccine, which was registered to great Kremlin fanfare in August despite concerns about underlying data and unfinished clinical trials, insist the issues should not stand in the way of a rollout.
In the Czech Republic, Prime Minister Andrej Babis on April 7 announced the dismissal of a health minister who was reportedly resisting pressure -- including public complaints by President Milos Zeman -- to order Sputnik V.
The German state of Bavaria recently announced an agreement to buy 2.5 million doses of Sputnik V pending approval by European regulators.
The Twitter account for Sputnik V later said the RDIF had begun negotiations with the German government "on the advance purchase agreement" of the vaccine.
There was no immediate confirmation of the announcement from the German government.
Last week, Chancellor Angela Merkel spoke with Russian President Vladimir Putin by phone, with the registration of Sputnik V vaccines, the possibility of its shipments, and joint production in EU nations being among the topics discussed, according to readouts from Berlin and Moscow.
Russia's own campaign to vaccinate its population with Sputnik V is going unexpectedly slowly, with many Russians resisting calls to get vaccinated, citing government distrust.