The FDA is reportedly preparing to add a boxed (black box) warning to one or more Covid-19 vaccines, according to two people familiar with the agency’s plans. The move has been tied in reports to CBER and to internal memos from senior vaccine officials, and sources say the decision may be announced before year-end. The accounts name Vinay Prasad, director of the FDA’s Center for Biologics Evaluation and Research, as a key architect of the internal review. The draft actions described in media reports are under review at multiple levels inside the Department of Health and Human Services. Outside experts and professional societies voiced alarm in reaction to the media coverage, noting that boxed warnings are the agency’s most serious safety advisory and have major implications for public confidence and vaccine uptake. The FDA has not finalized or publicly issued the warning and Department officials called some reports speculative.