BioNTech SE (BNTX) shares fell sharply by 5.02% during Monday's trading session, mirroring declines across the vaccine sector following the FDA's announcement of stricter approval requirements for vaccines.

The drop comes after Dr. Vinay Prasad, the FDA's top vaccine regulator, linked COVID-19 shots to the deaths of 10 children in an internal memo. The agency plans to impose additional safety tests for vaccine approvals, particularly for flu and pneumonia vaccines, raising concerns about increased costs and delays for manufacturers like BioNTech.

Analysts note the FDA's shift under Health Secretary Robert F. Kennedy Jr., a vaccine skeptic, could further pressure BioNTech's COVID-19 business. Other vaccine makers, including Moderna and Novavax, also saw significant declines.