NEW YORK / December 2, 2025 — Shares of major vaccine makers fell on Monday after the U.S. Food and Drug Administration (FDA) indicated it plans to tighten vaccine approval standards.

An internal memo from Dr. Vinay Prasad, the FDA’s top vaccine regulator, linked Covid-19 vaccines to the reported deaths of 10 children between 2021 and 2024, according to the Vaccine Adverse Event Reporting System (VAERS). The memo also outlined proposed changes to the FDA’s vaccine evaluation process, as reported by multiple media outlets.

The Department of Health and Human Services, which oversees the FDA, did not immediately comment.

Following the news, Moderna shares fell 3.3%, Novavax dropped 2.3%, and U.S.-listed BioNTech shares were down 1.4%. Pfizer stock remained largely unchanged, while the SPDR S&P Biotech ETF slipped 1.3%.

Moderna and other pharmaceutical stocks previously declined in May after the FDA appointed Prasad—known for his critiques of the U.S. Covid-19 response—to lead the Center for Biologics Evaluation and Research.