The chief executive of British pharmaceutical company AstraZeneca Plc, Pascal Soriot, has defended the company's decision to prioritise COVID-19 vaccine deliveries to the UK, after the European Union voiced growing frustration over delivery delays, CNN reported on Wednesday.

Soriot was quoted as telling the Italian newspaper la Repubblica on 26 January 2021: "The UK agreement was reached in June, three months before the European one. As you could imagine, the UK government said the supply coming out of the UK supply chain would go to the UK first", adding, "The contract with the UK was signed first and the UK, of course, said 'you supply us first,' and this is fair enough. This vaccine was developed with the UK government, Oxford and with us as well."

EU Health Commissioner, Stella Kyriakides, had expressed dissatisfaction on talks with AstraZeneca, saying that the company "intends to supply considerably fewer doses in the coming weeks than agreed and announced" due to production problems.

Soriot conceded to la Repubblica that the company had to reduce supply to the EU as a result of reduced yields early in the manufacturing process at one site in Europe.

He added that they also faced "teething issues" with the UK supply chain, but they had a "head start" since they signed the contract earlier, and had more time to "fix all the glitches."

With production issues cantered around AstraZeneca's European plants, Soriot said the company could soon be able to begin using its UK site to help Europe once the UK has "reached a sufficient number of vaccinations."

So far, the EU has ordered 300 million doses of the AstraZeneca vaccine, which could be approved for use by the European Medicines Agency (EMA) as soon as this week, with an option to purchase an additional 100 million doses.