(FILES) This file illustration picture taken in Paris on November 23, 2020 shows a syringe and a bottle reading "Covid-19 Vaccine" next to AstraZeneca company and University of Oxford logos. - The Covid-19 vaccine developed by the British drugs group AstraZeneca and the University of Oxford has achieved a "winning formula" for efficacy, the company's chief executive said on Sunday, December 27. (Photo by JOEL SAGET / AFP)