AstraZeneca Plc stopped giving shots of its experimental coronavirus vaccine after a person participating in one of the company’s studies got sick, a potential adverse reaction that could delay or derail efforts to speed an immunization against Covid-19 for the world. The pause stemmed from a standard review of the company’s vaccine trials after one person developed an unexplained illness, AstraZeneca said in a statement. The move was intended to give researchers time to examine safety data while maintaining the integrity of the trials, the company said.