New research has confirmed that an experimental pneumonia vaccine specially formulated for the developing world could save the lives of children in Africa.

However, the vaccine is unlikely to have any future because its manufacturer, Collegeville, Pa.-based Wyeth Pharmaceuticals, has decided instead to pursue a more broadly protective vaccine targeting 13 strains of the pneumonia bug. The study, published this week in The Lancet medical journal, tested the experimental vaccine on more than 17,000 children in Gambia and found it reduced the chances of getting pneumonia by 37 percent and cut deaths by 16 percent. Pneumonia is a major killer of children in the developing world.

The results bolstered the findings of two earlier studies of the vaccine in South Africa and in California.

A children's pneumonia vaccine is already available, and is widely used in the United States. But it is not used in the developing world.

That vaccine, also made by Wyeth, targets seven strains of the pneumonia bug. The test vaccine used in the Gambia study targets nine strains, adding two that are common in Africa but not important in richer countries.

The licensed seven-strain vaccine is not used in Africa because health authorities there have been hoping the nine-strain shot would become available soon, said the study's leader Dr. Felicity Cutts, who now works for the World Health Organization.

"The problem with the seven-valent (strain) vaccine is that it is expensive," Cutts said. "And it's only made by one manufacturer, who already has difficulty producing enough for the American market."

A spokeswoman for Wyeth said Friday that the company plans now to develop a 13-strain vaccine instead. That vaccine is already being tested on people. But its trials are in the early stages and it will be several years before it could be made available.

The studies with the nine-strain shot demonstrated that strains can be added safely to the vaccine without compromising its effectiveness, so the company plans to broaden the target, said Wyeth spokeswoman Natalie de Vane.

Cutts said that because the nine-strain shot has no future, it is likely that health advocates will now push instead for the seven-strain children's vaccine now available to be used in Africa and for wealthy countries to provide the money to buy it.

If it is used in Africa, the existing vaccine can be expected to be about three-quarters as effective as the one tested in the Gambia trial, Cutts said.

Editor: Catherine