Two major clinical trials for experimental Covid-19 vaccines got back on track in the United States on Friday providing a glimmer of hope. AstraZeneca Plc and Johnson & Johnson plan to resume Covid-19 vaccine clinical trials that had been halted by US regulators, putting research into two of the leading candidates for a coronavirus inoculation back on track. AstraZeneca announced that the trial of its vaccine candidate, developed with Britain's University of Oxford, has resumed in the US, the only country where it remained suspended following a participant's illness six weeks ago. While Johnson & Johnson said in a statement that it is preparing to resume recruitment in a late-stage trial of its vaccine after consultation with the US Food and Drug Administration.