MILAN (Reuters) - Europe’s drug regulator is auditing the manufacturing site of the Serum Institute of India (SII), a source with knowledge of the matter said, a necessary step before AstraZeneca’s COVID-19 vaccine made there can be exported to the bloc. SII, the world’s largest vaccine manufacturer, is producing the AstraZeneca vaccine, developed with Oxford University, for dozens of poor and middle-income countries. The precise reason for the audit of SII’s manufacturing processes and facilities was not clear, but a green light would mean the drug could be exported to the European Union, the source said, declining to be identified because the review is confidential. The EU and Britain are mainly supplied by local facilities, but production problems have cut deliveries by the British-Swedish drugmaker to the EU, forcing it to look elsewhere. The European Medicines Agency (EMA) and European Commission, which has overseen the bloc’s supply contract with AstraZeneca, declined to comment specifically on the audit. But spokespeople for both organisations confirmed in emails the EMA would need to approve the site and change marketing authorisation for the shot to be exported to the bloc. A drugmaker would have to submit an application to the EMA to approve the change, the EMA spokesman said. SII and AstraZeneca both declined to comment on the matter. On Thursday, AstraZeneca chief executive Pascal Soriot told EU lawmakers he hoped to boost shipments to the 27-nation bloc in the second quarter, after the drop in the first three months of the year. Under its contract with the EU, the company has committed to delivering 180 million doses in the second quarter. He said the company will increase output in the second quarter using factories outside the EU that had no production problems, including in the United States. Slideshow ( 3 images ) He did not mention SII. A senior EU official involved in talks with AstraZeneca told Reuters previously that SII could be a potential supplier. The Commission spokesman said the advance purchase agreement (APA) the EU has with AstraZeneca allows for manufacturing to happen elsewhere if authorised by EMA. “We therefore continue to discuss with the company possible ways to deliver the doses in line with the EU regulatory framework, with the APA and with our international commitments,” he said in the email. News of the audit comes after Reuters reported last month that the British drug watchdog has also been carrying out checks on the factory. The EMA has been evaluating the Serum plant for a week and could be finished by March, the source said. “You have to look at all the steps of production. The process right now is in a phase of virtual contacts and data requests,” he said. “No need for an in-person visit if the data are convincing.” As the UK’s Medicines and Healthcare products Regulatory Agency (MHRA) carried out an audit with a physical visit, that might be enough for the EMA not to have to make its own checks on the ground, as it is a trusted agency. Brussels has set a target of vaccinating 70% of the EU’s adult population by the end of the summer, but has struggled to secure the doses promised by Pfizer and its partner BioNTech partners and AstraZeneca. Last week, SII said it was prioritising domestic vaccine needs and asked for patience from foreign governments awaiting their supply of COVID-19 shots.