President Donald Trump, who seems intent on announcing a COVID-19 vaccine before Election Day, could legally authorize a vaccine over the objections of experts, officials at the Food and Drug Administration and even vaccine manufacturers, who have pledged not to release any vaccine unless it’s proved safe and effective.In podcasts, public forums, social media and medical journals, a growing number of prominent health leaders say they fear that Trump — who has repeatedly signaled his desire for the swift approval of a vaccine and his displeasure with perceived delays at the FDA — will take matt…