Pharma giant AstraZeneca has paused a clinical trial of its coronavirus vaccine after a volunteer developed an unexplained illness, the company said on Tuesday. AstraZeneca, which is developing the drug alongside the University of Oxford, is a frontrunner in the global race for a Covid-19 vaccine. The company said that the pause was a routine action which happen whenever there is a potentially unexplained illness in one of the trials. "It is investigated, ensuring we maintain the integrity of the trials," it said. It was not immediately clear where the patient was, or the nature and severity of their illness.