AstraZeneca Plc and the University of Oxford¡¯s COVID-19 vaccine won U.K. clearance, marking the first approval worldwide for a shot that¡¯s faced questions but will be key to mass immunizations.

The vaccine will be prioritized for the country¡¯s most vulnerable groups, with shots starting Monday, according to the government. It¡¯s the second coronavirus injection to be cleared for emergency use in the U.K. after Pfizer Inc. and BioNTech SE¡¯s in early December.

The move will help the U.K. ramp up vaccinations as a new surge in coronavirus infections strains hospitals. The country has reported record numbers of COVID cases this week, with a new variant of the pathogen raising concern globally.