According to a statement quoted by multiple outlets, the Robert Koch Institute’s standing vaccine commission said there had not been enough people over 65 enrolled in trials of AstraZeneca’s vaccine, which the drugmaker developed with scientists from the University of Oxford. As a result, it reportedly said it was recommending that the vaccine be used only on people ages 18 to 64.

“There is currently insufficient data available to assess the effectiveness of vaccinations from 65 years of age,” the commission, known as STIKO, was quoted as saying.

However, the Robert Koch Institute told Fortune that STIKO is still discussing the issue and will only publish a recommendation on Friday.

Also Friday, the European Medicines Agency (EMA) is expected to issue a recommendation on whether to approve AstraZeneca’s vaccine for emergency use—a decision that, if positive, will likely also include recommendations for use in the elderly. No EU country will go ahead with any AstraZeneca deployment without the EMA’s approval.

Multiple arguments

There has already been furious debate in Europe this week over the issue of AstraZeneca’s vaccine and older recipients, centered on the thoughts of the German government. According to some German media outlets, government officials have been anonymously claiming that the jab is only 8% to 10% effective in people over the age of 65. The German government has denied those reports, as have AstraZeneca and the University of Oxford.

The big difference now is that STIKO is reportedly citing a lack of data, rather than data showing poor results, for its caution.

It’s a characterization AstraZeneca staunchly denies.

“The latest analyses of clinical trial data for the AstraZeneca/Oxford COVID-19 vaccine support efficacy in the over 65 years age group,” an AstraZeneca spokesperson said in an emailed statement. “We await a regulatory decision on the vaccine by the EMA in the coming days.”

STIKO and the EMA’s recommendations also come as AstraZeneca has faced withering criticism from EU politicians over its handling of production snags that it has said will limit how many doses of the vaccine the company will be able to provide to Europe in the near term. The company had initially told the EU it would supply 80 million doses in the first three months of 2021, but now says production problems mean it is likely to be able to provide just two-fifths of that amount.

European countries have lagged many others in vaccinating their populations so far, and the bloc is eager to make up the gap. The EU had contracted with AstraZeneca for 300 million doses of its vaccine in total, with an option for an additional 100 million doses. It has told the company to divert supplies from manufacturing facilities in the U.K. and elsewhere to make up for the shortfall, something the company has said it cannot do.

The company has said that its contract with the EU required it only to make its “best effort” to meet the production targets, while the EU has said that AstraZeneca is contractually obligated to meet the schedule and threatened to take legal action against the company. The bloc is also in the process of tightening export restrictions to prevent vaccine doses made in the EU from being shipped elsewhere, though the details of possible exemptions—likely including humanitarian exports—are still to emerge.

A phone call on Wednesday between EU and company officials failed to resolve the impasse, with Stella Kyriakides, the bloc’s health commissioner, tweeting after the call that “we regret the continued lack of clarity on the delivery schedule and request a clear plan from AstraZeneca for the fast delivery of the quantity of vaccines that we reserved for Q1.”

The Commission also wants AstraZeneca to allow the publication of their confidential contract, to make it clear what was promised and what was not.

Data fears

The concerns from the German advisory committee are only the latest doubts raised about the efficacy of AstraZeneca’s COVID-19 immunization. The company sowed confusion when it announced in late November that clinical trials in the U.K. and Brazil had shown that the vaccine was 70% effective “on average” when given as two doses. That figure blended results from different trials with different protocols.

The company caused further consternation when it admitted that the protocol it said was 90% effective in fact involved administering a half-dose shot, followed weeks later by a full dose, and that that dosage pattern had been the result of a mistake in measuring dosages. That half-dose, full-dose protocol was used for only a fraction of the clinical trial participants. For those who received the two full doses, the vaccine was just 62% effective.

The figures were far below the 95% effectiveness figures presented by two other leading coronavirus vaccines produced by Pfizer and Moderna. The AstraZeneca clinical trials were also smaller than those conducted by those other companies, and enrolled fewer participants over the age of 65. That age group is particularly important because they are the most likely to become severely ill from COVID-19.

While the U.K. medical regulator decided to go ahead and authorize use of the AstraZeneca vaccine, which was widely portrayed in British media and by British politicians as a homegrown champion, the U.S. Food and Drug Administration, apparently concerned by the muddled clinical trial data, has so far declined to authorize use of AstraZeneca’s shot. The company is hoping the FDA will do so after the conclusion of a larger-scale clinical trial it is conducting in the U.S.

When it authorized British use of the vaccine at the end of 2020, the U.K.’s Medicines and Healthcare product Regulatory Agency (MHRA) noted that AstraZeneca’s trial was light on older participants—of the roughly 12,000 that were dosed in large-scale trials, only 660 were age 65 or over.

“The number of COVID-19 cases (2) in 660 participants ≥65 years old were too few to draw conclusions on efficacy,” the MHRA said in its guidance for doctors.

But faced with the same data issue, the British agency appears to have made a very different call to the Germans.

“Current evidence does not suggest any lack of protection against COVID-19 in people aged 65 or over,” the MHRA told Fortune. “The data we have shows that the vaccine produces a strong immune response in the over 65s.

“More data is continually becoming available for this age group and our Public Assessment Report, available on our website, will be updated to reflect this.”

Note: This article was updated to include the MHRA’s statement.