An experimental vaccine that protects against a nasty stomach virus that hits one in five people annually has shown promise in early clinical trials, researchers say.

The vaccine against norovirus developed by the Center for Infectious Diseases and Vaccinology at Arizona State University generated good immune response in early studies of a few hundred people, said Dr. Charles Arntzen, a member of the research team, at the annual meeting of the American Association for the Advancement of Science in Vancouver.

Norovirus is also known as "cruise ship virus" for its notorious ability to make hundreds of passengers sick. (Wolfgang Rattay/Reuters)

Norovirus, which causes cramps, vomiting and diarrhea, is also known as "cruise ship virus," and is notorious for its ability to make hundreds of passengers sick at a time. Each year, it hits an estimated 20 per cent of the population and is responsible for millions of hospitalizations in North America.

Noroviruses are believed to cause about half of all food-borne disease outbreaks in the U.S. and 90 per cent of non-bacterial gastroenteritis worldwide.

Sixty per cent of infections occur in long-term-care homes, and the disease can be particularly deadly for the elderly, said Jan Vinje, head of the gastroenteritis and respiratory viruses lab at the U.S. Centers for Disease Control and Prevention in Atlanta.

Vaccine applied as nasal spray

Arntzen said his research group's vaccine, which is applied as a nasal spray and doesn't require any needles, still needs to be tested in larger trials. The researchers also need to optimize the dosage, figure out how long the immunity against norovirus lasts, and prove it is effective against emerging new norovirus strains before government agencies approve its use.

Arntzen, who presented his research at the conference on Friday, estimated that approval is likely four or five years away.

Vinje said norovirus kills about 800 people a year in the U.S. — far fewer than the seasonal flu. But he thinks a vaccine could still be "really helpful" for targeted populations such as health care and food industry workers or the elderly.

The Arizona State University vaccine is made in tobacco plants and is made up of components called virus-like particles.

They mimic actual noroviruses and stimulate an immune response without producing any symptoms.

The vaccine is one of two experimental norovirus vaccines under testing in the U.S. The other was developed in Montana.