AstraZeneca and top supplier defend vaccine production

The EMA's inquiry follows concerns about blood clots and other possible side-effects that have prompted many European countries to suspend or limit use of the AstraZeneca vaccine. The regulator has said the adverse incidents are unlikely to be linked to the vaccine.

AstraZeneca said each batch went through "more than 40 different quality control tests" from the laboratory to being administered.

"Every batch made in our supply network must meet the same exacting production and quality standards," the company told the Financial Times.

"Regular quality control testing is carried out at every stage of production, to ensure the production process is well controlled and results are consistently within required levels. Each of these tests have been validated and has a specific step-by-step process that must be carried out."

The US company Catalent runs one of the "fill and finish" centres where the vaccine's active ingredient is used to create the drug, which is put into vials. Catalent's plant in Italy produced two of the batches that triggered suspension of vaccines in Austria and Italy, the FT said.

The head of Catalent's European biologics division, Mario Gargiulo, told the FT every batch shipped from the Italian plant met rigorous quality standard and tests.

"All documentation and quality assessments pertaining to these batches were once again reviewed by Catalent, AstraZeneca and the Italian regulator AIFA," he told the paper.

EU states' halting of the AstraZeneca jab has become mixed up in politics, including tensions between the EU and the UK. Germany's role is in the spotlight after the EU's biggest states agreed to put the vaccine on hold despite experts saying it was needed to stop a resurgence of infections.

“We are worried that there may be an effect on the trust of the vaccines,” Emer Cooke, head of the EMA, said, according to Reuters. “But our job is to make sure that the products that we authorise are safe and can be trusted.”

Italy is reported to have suspended the vaccine after a call between German chancellor Angela Merkel and Italian prime minister Mario Draghi, leading an Italian health official to say Draghi decided to align himself with Merkel.

Ian Jones, a professor of virology at Reading University in the UK, told Reuters questions about blood clots had been "picked up by politicians who don’t know one side of a virus from another". Once one or two countries said there was a problem others followed like dominoes, he said.

AstraZeneca shares fell 1.7% to £71.11 at 14:55 GMT.