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Norovirus Spreads Through Crowded Populations, With Children, Seniors at Risk of Becoming Severely Ill
By Laird Harrison
WebMD Health News
Reviewed by Laura J. Martin, MD
Dec. 7, 2011 -- An experimental vaccine has passed an important test in preventing symptoms and infection from a type of norovirus, one of the most common causes of diarrhea and vomiting, researchers say.
The disease often sweeps through cruise ships, nursing homes, and other areas where a lot of people live close together.
In a new study, researchers sprayed the vaccine in the noses of 47 volunteers. They also sprayed a placebo vaccine in the noses of 43 other volunteers. The study participants all swallowed a large dose of the norovirus.
About a third of the participants who got the real vaccine developed gastrointestinal symptoms such as diarrhea and vomiting related to norovirus, compared to about two-thirds of those who got the placebo vaccine.
The results are very promising, but researchers have a few more years of research to do before the vaccine can be offered to the public, researcher Robert Atmar, MD, tells WebMD.
"I was very happy that we were able to demonstrate, at least as a proof of concept, that the vaccine can prevent some disease," says Atmar, a professor of infectious diseases at the Baylor College of Medicine.
Atmar and his colleagues published the findings in The New England Journal of Medicine. The study was funded by LigoCyte Pharmaceuticals, a research company in Bozeman, Mont., that hopes to bring the vaccine to market.
A Real Need for the Vaccine
The vaccine is made from some of the proteins that surround the virus, without the genetic material that the virus needs to reproduce.
A successful vaccine against noroviruses could prevent a lot of suffering. Most infected people suffer a couple of days of vomiting and diarrhea, but children, the elderly, and other people with low resistance can become severely ill. Worldwide, noroviruses send up to 1.1 million people to the hospital and kill more than 200,000 children every year.
There is no way of treating the infection; health care workers can only relieve the symptoms. Thorough hand-washing is one of the best ways to prevent it. Washing fruits and vegetables and cooking shellfish before eating can also help prevent infection.
Robert Frenck, MD, a professor of pediatrics who researches noroviruses at the University of Cincinnati, tells WebMD that the results of the vaccine study are an important step toward preventing the disease. "This is early, but it's encouraging," says Frenck, who was not involved in Atmar's study.
Not only did fewer of those who got the real vaccine get sick to the stomach, their symptoms were about one-third milder than those who got the placebo.
But the results leave questions to be answered:
- How long will the benefits of the vaccine last? It is possible that people will need to take the vaccine repeatedly, much like an annual flu shot, to stay protected.
- Will the same type of vaccine work against other strains of norovirus? This study only looked at one strain of the virus, known as the Norwalk strain. Researchers plan to test it in additional strains.
The vaccine could be especially useful for populations such as soldiers or the elderly, Frenck says.
"I was in the Navy for a number of years," he says. "This virus can go right through ships," rapidly infecting nearly everyone.
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