European Commission chief Ursula von der Leyen insisted Wednesday that problems dogging vaccine supplies to the EU can be resolved, after AstraZeneca said it could deliver only half of its expected amount in the second quarter.

AstraZeneca said Tuesday it would look to make up the shortfall from supply chains other than those that now serve the 27-nation European Union.

A spokesman for the British-Swedish drugs group told AFP that AstraZeneca was "working to increase productivity in its EU supply chain" and would use its "global capability in order to achieve delivery of 180 million doses to the EU in the second quarter.

"Approximately half of the expected volume is due to come from the EU supply chain" while the remainder would come from its global supply network, he added.

Ahead of a virtual EU summit on the Covid-19 pandemic, von der Leyen sought to calm impatience over the bloc's stuttering vaccine roll-out.

"Vaccine manufacturers are our partners in this pandemic and they have also never faced such a challenge," she told the German regional daily Augsburger Allgemeine.

"New questions are always arising that we can generally resolve amicably," she said, adding that she was "optimistic".

Von der Leyen advocated "working together with the companies to ensure global production is improved".

The announcement follows controversy over first-quarter deliveries of the AstraZeneca-Oxford University jab to the EU, which has caused tension between the bloc and the pharmaceutical company.

AstraZeneca's EU supply chains will only be able to provide half of the expected doses for the second quarter, but the shortfall will be made up from its global capacity
AstraZeneca's EU supply chains will only be able to provide half of the expected doses for the second quarter, but the shortfall will be made up from its global capacity AFP / JENS SCHLUETER

Before the EU approved the vaccine in late January, the company sparked fury among European leaders by announcing that it would miss its supply target of 400 million doses due to a shortfall at the firm's European plants.

The disagreement also caused diplomatic tensions with Britain, which definitively left the EU after 40 years of membership -- with Brussels implicitly accusing AstraZeneca of giving preferential treatment to Britain at the bloc's expense.

The UK government has vaccinated millions of Britons with the AstraZeneca jab since late last year.

But the company only began shipping it to the EU in early February, after the bloc's drug regulator took its time issuing a recommendation.

The AstraZeneca vaccine has suffered a number of setbacks -- it was temporarily excluded from South Africa's immunisation campaign because of concern it was less effective against new virus variants there.

Meanwhile Germany's vaccine commission recommended it only for people aged 18 to 64 years old.

German demand for the jab has been affected as a result. Some 1.4 million doses of AstraZeneca vaccines have been delivered but on Tuesday, official data showed only 239,000 had been administered.

Recently however, World Health Organization experts recommended it for use with people aged over 65 and in settings where new strains of the virus are circulating.

The shot forms the bulk of doses being rolled out around the world -- especially in poorer countries -- under the Covax programme.

It has drawn praise for its low cost relative to rivals and lighter logistics requirements because it can be stored in a regular refrigerator.

On February 11, AstraZeneca said its annual profit had doubled in 2020.