A new vaccine against rotavirus, a diarrheal disease that kills about 600 children a day, has been shown to have almost 67 percent efficacy in preventing the illness. "This efficacy of about 70 percent is higher than any other vaccine in similar settings," said Dr. Emmanuel Baron, director of Epicentre, the research arm of Doctors Without Borders, which conducted the trial. A clinical trial of 3,500 infants in the African country of Niger showed the efficacy of the new vaccine, known as BRV-PV, to be 66.7 percent. Thirty-one cases of rotavirus were reported among children who got the vaccine, compared with 87 cases among those who received a placebo. Details of the study and the vaccine's effectiveness were published in the New England Journal of Medicine. "We saw actually three things," Baron said. "The first is that this vaccine is efficient. The second is that this vaccine is safe. And we also saw a good acceptability by the care providers and the families." An estimated 450,000 young children and babies die each year of diarrheal diseases. One of them is rotavirus, which causes a severe infection of the gastrointestinal tract. Experts say rotavirus is responsible for about 37 percent of deaths among children younger than 5 who succumb to diarrheal diseases each year, or about 215,000 deaths annually. There are two existing vaccines, but Baron said they are not widely used, as they are relatively expensive and must be refrigerated. Refrigeration is an obstacle in many African countries where rotavirus is most pronounced because electricity there is unreliable. Even when children are immunized with the older vaccines, Baron says, hundreds die each day around the world. The new vaccine does not need refrigeration for up to six months, because it is mixed or reconstituted with liquid before it is given to children in a three-dose schedule, at 6, 10 and 14 weeks of age. Initially, the BRV-PV is expected to cost $6 dollars for the three shots, a price that is expected to drop as the vaccine gains traction. Baron said clinicians in countries where rotavirus is a serious health threat are waiting for the green light from the World Health Organization to begin immunizing children with the new vaccine.