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Cholera Vaccine Protects in Vietnam

An inexpensive cholera vaccine has performed well in a pilot trial in Vietnam. The finding, reported in tomorrow's issue of The Lancet, is a big advance in the long and frustrating search in developing countries for a useful vaccine against cholera, a potentially fatal illness spread through contaminated drinking water.

In late 1992, a team led by researchers at the National Institute of Hygiene and Epidemiology in Hanoi, Vietnam, and the U.S. National Institute of Child Health and Human Development gave the oral vaccine--which consists of killed whole Vibrio cholerae, the cholera bacterium--to more than 67,000 residents of Hue, Vietnam. A roughly equal number did not receive the vaccine. During 1993, 37 vaccinated people were admitted to a hospital with cholera, compared to 92 cases in the control group. Thus the vaccine decreased hospital admissions for cholera by 60%.

Developed and produced at the institute in Hanoi, the vaccine is relatively cheap to produce and is easy to distribute because it remains active without refrigeration. It also appears to be equally effective in children and adults. This surprised the researchers, because a similar whole, killed vaccine tested in Bangladesh in the 1980s appeared to be less potent in children.

"This study is important," says Myron M. Levine, director of the Center for Vaccine Development at the University of Maryland School of Medicine, "because it demonstrates that a developing country can design, produce, and evaluate a moderately effective vaccine in a large field trial with little external assistance."

The researchers plan to launch a larger trial in Vietnam later this year pitting the vaccine against a placebo. If proven effective, the vaccine could be pressed into duty quickly in Vietnam, where more than 3000 people get cholera each year. Levine adds that a similar vaccine against other cholera strains could be produced in developing countries such as Zaire, where an outbreak killed 12,000 people in Rwandan refugee camps in July 1994.