epa08966496 (FILE) - A nurse prepares a dose of the Oxford/AstraZeneca Covid-19 vaccine at the NHS vaccine mass vaccination centre that has been set up in the grounds of Epsom Race Course, in Surrey, Britain 11 January 2021 (reissued 26 January 2021). AstraZeneca has denied reports of a reduced efficiacy of its COVID-19 vaccine.  EPA/DOMINIC LIPINSKI / POOL