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Neutralizing noroviruses

Researchers found a potential weakness in norovirus, the leading cause of vomiting, diarrhea, and foodborne illness. New Africa / Shutterstock

Noroviruses are highly contagious. They spread easily through contaminated food and water. The viruses can also live on surfaces for up to two weeks. In the U.S., norovirus is the leading cause of vomiting, diarrhea, and foodborne illness. It causes about 2,500 outbreaks, sickening about 20 million people each year. Most people recover from infection within days, but norovirus can lead to severe illness in older people, young children, and people with weakened immune systems.

So far, there’s no approved vaccine for norovirus. It’s been difficult to develop an effective vaccine because the noroviruses that infect people can vary. There are at least four types of norovirus, and they can mutate rapidly.

To gain insights into the immune system’s response to the virus, an NIH-funded team led by Drs. George Georgiou and Juyeon Park at the University of Texas at Austin and Ralph Baric at the University of North Carolina, Chapel Hill studied two healthy young adults who had received an oral vaccine candidate for norovirus developed by Vaxart. Earlier tests suggested that these two participants had an unusually broad immune response to the vaccine. The team examined their immune responses to look for antibodies that could target a wide range of norovirus strains. Their findings were reported in Science Translational Medicine on March 5, 2025.

The researchers found antibodies in both people that could block multiple norovirus strains. One person made antibodies that could neutralize norovirus types responsible for 75% of outbreaks around the world.

A structural study of one of the broadly neutralizing antibodies (bnAbs) in complex with the virus’s protein shell, or capsid, showed where it bound the virus. The part of the norovirus structure bound by the bnAb is conserved—meaning it tends to stay the same—across diverse norovirus types.

“These findings provide critical insights into how the immune system responds to norovirus and pave the way for designing a vaccine that offers broad, long-lasting protection,” Georgiou says. “We found antibodies that are very broad in terms of being able to neutralize many different variants that have circulated or are circulating now.”

“Our findings can better inform the future design of vaccine development against norovirus,” Park adds.

The results also highlight a previously unknown weakness of the virus in its arms race against the human immune system. The discovery could inform the further development and design of vaccines that may work even better to produce protective bnAbs in more people. It also could lead to therapies to help people unable to fight norovirus infection on their own.

—by Kendall K. Morgan, Ph.D.