The German health ministry has admitted that there is no data to suggest the AstraZeneca vaccine is only 8% effective in people over the age of 65.
Daily papers Handelsblatt and Bild both reported that the vaccine only had an efficacy of 8% or less than 10%, respectively, in those over 65.
Bild also reported that German officials were concerned that the vaccine might not receive EU approval from the European Medicines Agency (EMA) for use in those over 65.
It comes as a row has erupted between the UK and EU over vaccine supplies.
Watch: EU threatens export controls on coronavirus vaccines amid AstraZeneca row
The bloc has threatened to stop the exports of the US-developed Pfizer vaccine, which is being manufactured in Belgium, to the UK after AstraZeneca told the EU it could not meet agreed supply targets up to the end of March due to vaccine production problems.
In a written response to the German media reports, AstraZeneca described the claims as “completely incorrect”.
Now, the German health ministry has admitted there is no data to suggest the vaccine only has 8% efficacy in older people.
In a statement on Tuesday, quoted by several media outlets, the ministry said: “At first glance, it seems that the reports have mixed up two things: about 8% of those tested in the AstraZeneca efficacy study were between 56 and 69, only 3-4% over 70."
The health ministry also reiterated that it expects the EMA to decide on Friday whether to approve the vaccine.
Frustration has already been growing among European countries because Pfizer and partner BioNTech also announced a temporary slowdown in vaccine supplies earlier in January.
AstraZeneca said on Monday its chief executive had told the EU it was doing everything it can to speed up the process.
The company said the UK’s Joint Committee on Vaccination and Immunisation supported the vaccine’s use in the elderly. It also said that a strong immune response to the vaccine had been shown in blood analysis of elderly trial participants.
AstraZeneca’s main British trial started testing on adults no older than 55 because it initially focused on healthcare personnel and frontline workers in active duty.
Elderly trial participants were recruited later so that infections, which are needed to arrive at reliable efficacy data, were also coming in later.
Watch: Moderna says its vaccine works against new variants
Researchers at Oxford University said in a paper published in medical journal The Lancet on 8 December, when details of key vaccine trials held in the UK and Brazil were released, that efficacy data based on infections in the elderly were still limited.
“Efficacy data in these cohorts are currently limited by the small number of (infection) cases, but additional data will be available in future analyses,” they said in the paper.
Germany's health minister Jens Spahn said on Tuesday he supports EU proposals to introduce restrictions on COVID-19 vaccine exports.
He told ZDF television: "I can understand that there are production problems but then it must affect everyone in the same way.”
"This is not about Europe first but about Europe's fair share," he said, adding it, therefore, made sense to have export limits on vaccines.
The UK's vaccines minister, Nadhim Zahawi, insisted that the potential blockade would not affect the UK's rollout – although he admitted that supply was still "tight".
He also urged against "vaccine nationalism", noting that the world must be protected – a sentiment that was echoed by French MEP Véronique Trillet-Lenoir.
Watch: UK government ‘confident’ in Pfizer jabs supply despite EU threat to block exports