Vaccine maker Moderna said late last week that a phase 3 trial for its investigational mRNA norovirus vaccine candidate did not meet statistical criteria for early success.
But the trial will continue.
“The trial is ongoing and remains blinded as the Company works toward enrolling an additional cohort,” the company said in an update on its second quarter 2026 financial results.
The phase 3 trial for mRNA-1403, a trivalent norovirus vaccine, launched in September 2024. The company aims to recruit up to 20,000 participants ages 60 years and older and an additional 5,000 aged 18 to 59 from countries in both the northern and southern hemispheres to assess the vaccine’s ability to protect against moderate to severe illness caused by norovirus. But the study has faced a clinical hold over a single case of Guillan-Barre syndrome and challenges with recruiting patients.
According to reporting by Endpoint News, company officials said in a conference call that additional patients are needed because there haven’t been enough infections to adequately assess the efficacy of the vaccine.
Norovirus is the leading cause of vomiting and diarrhea from acute gastroenteritis among Americans of all ages and causes 58% of all foodborne illnesses in the United States, according to the Centers for Disease Control and Prevention. An estimated 2,500 reported norovirus outbreaks occur in the United States each year.