A key U.S. Food and Drug Administration official who oversees vaccines and biotech treatments will step down from the agency following multiple decisions that raised concerns within the industry. Vinay Prasad, director of the Center for Biologics Evaluation and Research, will leave the FDA at the end of April, an agency spokesperson confirmed on Friday. It is his second departure from the position: He briefly left the post in July following backlash over his regulatory decisions, and returned