BOSTON (AP) – The U.S. Army has carried out a promising early test of the first vaccine against hepatitis E, a form of the liver-attacking disease that sickens many Asians and can spread to soldiers or other Western visitors to the region.

The vaccine, made from moth cells infected with an engineered virus, was 96 percent effective for Nepalese Army soldiers who took all three doses. However, the disease wasn’t widespread even in a group without the vaccine: only 7 percent got sick.

The two-year test on 1,794 soldiers – almost all men – is reported today in The New England Journal of Medicine.

Though rarely fatal for most people, the disease can cause nasty stomach symptoms and pose special danger to pregnant women.

It’s not yet clear how long this vaccine’s protection might last or whether its benefits would justify its cost. Also, other side effects might be apparent in larger populations.

The study was funded by the U.S. Army and National Institutes of Health. The drug’s developer, GlaxoSmithKline PLC, also gave funding and participated in the research.