The University of Oxford and AstraZeneca Plc have restarted a UK trial of an experimental Covid-19 vaccine after it was halted over concerns about a participant who fell ill.The UK Medicines Health Regulatory Authority recommended that the trials resume after an independent review of the safety data triggered a pause on September 6, Oxford said in a statement. It declined to disclose details about the volunteer’s illness.While temporary halts are common in vaccine trials, the interruption to…