From this Reuters article, writer Maggie Fox explains the research results.
The two studies show they would also be effective in places without sure supplies of clean water or medical care, where diarrhea is one of the major killers of young children.
Victor's team tested Merck's RotaTeq vaccine in the rural area of Matlab in Bangladesh and urban and semi-urban parts of Vietnam.
About 2,000 babies aged one to three months got either three oral doses of the vaccine or placebo. After two years, 38 vaccinated babies got severe rotavirus infections, compared to 71 babies that got placebo, making the vaccine 48 percent effective against severe disease.
Dr. George Armah of the University of Ghana, along with colleagues at PATH and elsewhere, tested RotaTeq in 5,400 children in Ghana, Kenya, and Mali. There, the vaccine was 39 percent effective in preventing severe disease, and 64 percent effective in babies a year old or younger.
"In Africa, where young children are dying from diarrheal disease and prompt medical care is often out of reach, the need to prevent rotavirus is especially urgent," they wrote.
Rotavirus vaccination, along with programs that are about to start to vaccinate children against the most common causes of meningitis, pneumonia and other bacterial infections, "could instigate a new era of reduction of childhood disease and mortality," they wrote.