LONDON - BioNTech is studying whether the COVID-19 vaccine it developed with Pfizer helps prevent infection from the virus, a senior executive said on Wednesday as the company defended Britain's regulatory process for emergency approval.

Chief executive and co-founder Ugur Sahin said in a briefing he will have results of the study into prevention in three to six months.

The comments come after Britain gave the vaccine approval for emergency use on Wednesday, jumping ahead of the United States and Europe to become the West's first country to formally endorse a jab.

The European Union has criticised the rapid process, saying its own procedure was more thorough.

"The MHRA asked the same level of detailed questions as any other agency and focused on efficacy, tolerance, and the quality of reduction," chief business and chief commercial officer of the German biotech Sean Marett.

"These three elements are key elements to any vaccine that any regulator will look in detail and I think the MHRA has been no different in this respect."

(Reporting by Alistair Smout in London, John Miller in Zurich, Ludwig Burger in Frankfurt and Matthias Blamont in Paris; Writing by Josephine Mason in London, editing by Louise Heavens) ((Josephine.Mason@thomsonreuters.com; +44 207 542 7695; Reuters Messaging: josephine.mason.reuters.com@reuters.net))