NoroRecent norovirus outbreaks across the globe have heightened interest in vaccines against this highly contagious stomach virus. However, the path to an effective vaccine continues to present scientific and safety challenges.
Last week, pharmaceutical giant Moderna announced that its Phase 3 clinical study for their mRNA-based trivalent norovirus vaccine (mRNA-1403) has been placed on clinical hold by the U.S. Food and Drug Administration (FDA), according to an article in vax-before-travel.com. This action followed a report of a single case of Guillain-Barré syndrome (GBS), which is currently under investigation. Despite this setback, Moderna does not anticipate delays in their efficacy readout timeline as enrollment in the Northern Hemisphere has been completed.
Stephen Hoge, M.D., Moderna’s president, said that “GBS does happen”, with 3,000 to 6,000 people developing the condition annually in the United States. Some cases have been associated with vaccinations. Since January 7, 2025, the FDA has required warnings about GBS risk in the prescribing information for certain approved RSV (respiratory syncytial virus) vaccines during the 42-day post-vaccination period.
According to the U.S. Centers for Disease Control and Prevention (CDC), GBS is a rare neurological disorder in which the immune system attacks nerves. While its exact cause remains unclear, it often follows viral or bacterial infections. Most patients recover fully, though some experience permanent nerve damage.
Other companies remain active in norovirus vaccine development. HillVax announced in November 2024 that it is exploring further development of its virus-like particle-based bivalent vaccine candidate. Meanwhile, Vaxart Inc. is preparing to begin a Phase 1 clinical trial in the first half of 2025 for its orally administered bivalent norovirus vaccine. The Vaxart candidate offers potential advantages as it generates both systemic and mucosal immunity and remains stable at room temperature.
Developing broadly effective norovirus vaccines has historically been difficult due to the genetic and antigenic diversity of noroviruses. This challenge remains significant as researchers work to address the approximately 20 million norovirus illnesses that occur annually in the United States alone.
The industry’s progress on norovirus vaccine development will continue to be closely monitored, particularly as travel-related outbreaks highlight the need for effective prevention strategies.
Commenting on this article, the nation’s leading norovirus lawyer said, “Despite the challenges, it appears that a vaccine for norovirus could appear in the near future, potentially bringing relief to millions around the globe.”
