Explainer: How does AstraZeneca's vaccine compare with Pfizer-BioNTech?

A medical worker shows a dose of the Pfizer-BioNTech COVID-19 vaccine at the Regional Military Specialty Hospital in San Nicolas de los Garza, on the outskirts of Monterrey, Mexico December 29, 2020. REUTERS/Daniel Becerril

ZURICH (Reuters) - Britain on Wednesday became the first country to approve AstraZeneca and Oxford University's home-grown UK COVID-19 vaccine, adding an easy-to-manage shot to the arsenal of a nation desperate for pandemic relief.

Even so, scientists - and regulators in Europe, following the Brexit divorce - are sceptical, given confusion over trial results earlier that left experts questioning the robustness of the data.