The World Health Organization reports 844,000 people in northeast Nigeria have been reached with one dose of oral cholera vaccine in an effort to prevent the fatal disease from spreading. The latest figures show nearly 4,000 suspected cases, including 54 deaths in the region. The week-long campaign that ended Monday was centered in a camp for internally displaced people in Maiduguri, the capital of Borno state, as well as in several local government areas nearby. World Health Organization spokesman Tarek Jasarevic says hundreds of thousands of people above age one have received the oral vaccine and will be protected against cholera for up to six months. He notes the number of people at risk of getting cholera within an affected population decreases sharply as more people are vaccinated. “Cholera vaccines are used as a preventive tool in areas with few or no cases, but at high risk of the spread of the disease,” said Jasarevic. “For example, there are neighboring areas that are more affected. Obviously, I think there is an issue of access. Security is a major constraint with the recent attacks on humanitarian staff.” The World Food Program suspended its operation in Borno state after aid workers were attacked in a camp for displaced people in Maiduguri at the end of August. The Boko Haram insurgency has killed more than 20,000 people and displaced more than two million since 2009. Jasarevic says the oral cholera vaccine is only one of the tools available to combat this disease. He says it should be combined with prevention activities, such as informing communities about the need for good sanitation and hygiene and providing them with access to safe water. He says the World Health Organization is establishing cholera treatment centers as another important element in containing this outbreak.