BioNTech SE (BNTX) shares dropped sharply by 5.02% intraday on Monday, mirroring declines across the vaccine sector. The sell-off followed reports that the U.S. Food and Drug Administration (FDA) plans to impose stricter approval requirements for vaccines, including those targeting COVID-19.

An internal FDA memo linked COVID-19 vaccines to rare heart conditions in children, prompting concerns about increased regulatory scrutiny. Dr. Vinay Prasad, the FDA's top vaccine regulator, highlighted safety risks in the memo, which has led to broader market apprehension about future vaccine approvals and sales.

Analysts note that the FDA's proposed changes could delay new vaccine launches and increase development costs for companies like BioNTech, which co-developed the Pfizer-BioNTech COVID-19 vaccine. The news has sparked a sector-wide downturn, with Moderna and Novavax also experiencing significant declines.