First, the phase 3 trial of Moderna’s norovirus vaccine had to endure a clinical hold. Now, the study has to head back for a second season in the Northern Hemisphere after failing to find enough cases down south.
Norovirus, often called “food poisoning” or the “stomach bug,” can cause major disruptions to a person's daily life, with severe cases potentially leading to hospitalization as a result of dehydration.
Moderna’s late-stage trial of its trivalent norovirus vaccine, dubbed mRNA-1403, launched in September 2024 as the norovirus season began in the Northern Hemisphere. The trial aims to recruit about 20,000 participants aged 60 years and older as well as 5,000 participants between the ages of 18 and 59.
The study since relocated to the Southern Hemisphere to track the norovirus season there, where Moderna's efforts have apparently hit a roadblock.
In Moderna’s third-quarter earnings release, the mRNA specialist said it was unable to “accrue sufficient cases” of norovirus in the south to complete the study.
The phase 3 trial will “now enroll a second Northern Hemisphere season (2025-2026) for additional case accruals,” the company explained.
It means the timing of the phase 3 readout “will continue to be dependent on case accruals," according to Moderna.
The struggle to identify cases of norovirus isn’t the only setback the trial has faced. In February, the study was placed on hold by the FDA following a case of a neurological disorder called Guillain-Barré syndrome. The syndrome has cropped up as a side effect in trials for respiratory syncytial virus vaccines like Pfizer’s Abrysvo and GSK’s Arexvy.
By May, Moderna had confirmed that the hold had been lifted.