A compound found in seaweed may be able to do what no vaccine has managed to achieve: stop norovirus before it can infect human cells, according to new research.
This is the conclusion of a new study by researchers from Australia’s Griffith University and the biotechnology firm Marinova.
Norovirus—often dubbed the “winter vomiting bug”—is the leading cause of acute gastroenteritis worldwide, responsible for millions of cases of vomiting and diarrhea each year.
It spreads rapidly in closed settings such as schools, hospitals and care homes. Despite decades of research, scientists have struggled to develop a broadly effective vaccine.
One reason for this is the virus’s ability to mutate quickly, meaning any immunity is often short‑lived.
The study focused on complex carbohydrates found in edible seaweeds, particularly fucoidan and ulvan, which are abundant in brown and green seaweeds.
In laboratory experiments, these compounds were shown to strongly inhibit norovirus from binding to human receptors—a critical first step in the infection process.
Norovirus causes illness by attaching to histo‑blood group antigens (HBGAs), sugar molecules found on the surface of cells lining the gut.
Once attached, the virus can enter cells and begin replicating. The seaweed compounds appear to work by mimicking those same sugars, effectively acting as decoys that trap the virus before it can latch onto human tissue.
The researchers found that as concentrations of the seaweed compounds increased, norovirus binding dropped dramatically, in some cases approaching zero.
Crucially, this blocking effect was seen across multiple major norovirus strains, including GII.4 and GII.17—two of the most common causes of outbreaks worldwide.
Experts said the findings are significant because they sidestep one of the biggest hurdles facing vaccine development. Instead of relying on immune memory, which can fade quickly and vary by strain, this approach targets the virus’s physical mechanism of infection. In theory, that could make it effective even as the virus evolves.
However, researchers warned against over‑interpretation. The work was conducted in laboratory settings, not in humans, and eating seaweed itself is unlikely to provide protection against norovirus. Fresh produce, including seaweed, can also be a source of contamination if not handled safely.
Still, the findings open the door to new possibilities. Seaweed‑derived compounds could one day be developed into preventive supplements, antiviral treatments, or food‑based interventions designed to reduce the risk of infection—particularly in high‑risk settings.
For now, public health experts stressed that basic precautions remain essential, including thorough handwashing and staying home when sick.
Do you have a tip on a health story that Newsweek should be covering? Do you have a question about norovirus? Let us know via [email protected].
Reference
Wimmer, B. C., Kidgell, J. T., von Itzstein, M., Haselhorst, T., & Hansman, G. S. (2026). Harnessing marine sulfated polysaccharides to inhibit norovirus: From seaweed to solution. Microbiology Spectrum. https://doi.org/10.1128/spectrum.02445-25