OXFORD — The University of Oxford said on Tuesday (April 6) it had paused a small UK trial testing the Covid-19 vaccine it developed with AstraZeneca in children and teenagers, as it waits for more data on rare blood clotting issues in adults who received the shot.

The trial disruption is the latest blow to the vaccine, once hailed as a milestone in the fight against the pandemic, after several countries restricted its use in light of reports of medical issues after inoculations.