Vaccine Might One Day Prevent 'Cruise Ship' Stomach Bug

Experimental vaccine reduced effects of norovirus in small study

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WEDNESDAY, Dec. 7 (HealthDay News) -- An experimental vaccine may one day help us say "bon voyage" to the dreaded "cruise-ship" tummy bug for good. New research suggests a vaccine to stave off the norovirus that has sickened many cruisers in recent years may be on the horizon.

Norovirus causes cramping, diarrhea and vomiting, and spreads easily from person to person, often in crowded, closed places like cruise ships. Each year, 21 million cases of norovirus occur in the United States, according to background information in the small new study published in the Dec. 8 issue of the New England Journal of Medicine.

"It is possible to prevent infection and illness with a vaccine for norovirus," said Dr. Robert Atmar, a professor of medicine and molecular virology at the Baylor College of Medicine in Houston. But many questions remain unanswered, he said. For example, "we have to figure out the best way to give it and how long protection lasts."

The new study included 98 people who received the vaccine or an inactive placebo. All of the participants tested positive for a gene that makes them more susceptible to the norovirus, the FUT2 gene.

Those who received the new vaccine were less likely to develop the stomach bug than their counterparts who received the placebo, the study showed. What's more, they were also affected by the bug less frequently than their counterparts who did not receive the vaccine. Of recipients, 70 percent of people responded to the vaccine as evidenced by antibody levels in their bloodstream.

The new vaccine is given as two doses three weeks apart via a nasal spray. There were no safety issues seen in the new study. Side effects included stuffy nose and sneezing and were equally likely to occur in those who received the placebo. The new study was supported in part by LigoCyte Pharmaceuticals, maker of the vaccine.

Over the last two years, norovirus outbreaks have been reported on cruise ships docking in Tampa, Fla., and Charleston, S.C., and a 2009 study published in the journal Clinical Infectious Diseases implicated poor restroom cleaning in the virus' spread.

Exactly who would, should or could receive this vaccine if it were to become available is not known. "We are a long way from that point," Atmar said. It potentially could be given to people before they set sail on a cruise or even annually to individuals who are at high risk for stomach bugs such as children, military personnel, health care workers and the elderly. "There are a number of studies that have to be done before this would be possible," he said.

Like the seasonal flu, there are many different strains of norovirus that circulate each year, Atmar noted, and the vaccines might need to be updated annually based on which strains are circulating.

Dr. Thomas Hooton, a professor of infectious disease at the University of Miami Miller School of Medicine, said that the norovirus is "a mess and spreads like wildfire." Hundreds of people can get sick in just a few days, he pointed out. "If a food handler contaminates the food on a cruise ship, it spreads like crazy. There is bad diarrhea and bad vomiting, and if they are not cleaned up properly, it can stick to surfaces and spread from person to person," Hooton said.

Clearly, there is a tremendous need for prevention, Hooton added. "Nobody wants to go on a cruise and be sick for the whole trip."

The new research may bring us one step closer to a vaccine, he suggested. "Further study is needed to answer questions such as who should get the vaccine and how long the protection lasts," Hooton concluded.

SOURCES: Robert L. Atmar, M.D., professor, medicine and molecular virology, Baylor College of Medicine, Houston; Thomas Hooton, M.D., professor of infectious disease, University of Miami Miller School of Medicine; Dec. 8, 2011, New England Journal of Medicine

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