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# Clinical Hold on Moderna Norovirus Vaccine
- URL: https://www.fdaweb.com/clinical-hold-on-moderna-norovirus-vaccine/
- Published: 2025-02-14T12:00:00.000Z
- Updated: 2026-09-14T14:53:16.000Z
- Author: David McFarland
- Tags: Biologics, #legacy-id-D5158667

FDA has placed a clinical hold on a Phase 3 study evaluating the efficacy, safety and immunogenicity of Moderna’s trivalent vaccine against norovirus (mRNA-1403) after a case of Guillain-Barré syndrome was reported. It is a two-season vaccine and the Northern Hemisphere portion of the study is fully enrolled, and the company says it is preparing the second season enrollment in the Southern Hemisphere. Guillain-Barré is a rare autoimmune disorder that causes the body's immune system to attack the nerves, and the case is under investigation, Moderna says.

Moderna says it does not expect the investigation to impact the study’s efficacy readout timeline, adding that the timing of the Phase 3 readout will be dependent on case accruals.