Two reports surfaced that FDA leadership is considering adding a boxed (black box) warning to one or more Covid-19 vaccines. According to agency insiders and media coverage, the proposal—attributed in part to the FDA’s acting biologics leadership—was under internal discussion and could be announced by year-end. The disclosures prompted immediate responses from public-health experts and manufacturers. Medical and academic clinicians interviewed called the move unprecedented given the extensive safety and effectiveness data for authorized Covid-19 vaccines, warning that a boxed warning could substantially reduce uptake. Companies such as Moderna issued statements highlighting ongoing safety monitoring by regulators worldwide. The FDA has not finalized or announced any action; HHS and FDA spokespeople characterized external reporting as speculative and emphasized their continued review of safety data.