Early Malaria Vaccine Tests

Medical Authors and Editors: Barbara K. Hecht, Ph.D. and Frederick Hecht, M.D.

October 15, 2004 -- A malaria vaccine has protected a significant percentage of children against uncomplicated malaria, infection, and even severe forms of the disease for at least six months, according to a proof-of-concept study published today in The Lancet. This was the largest malaria vaccine efficacy trial ever conducted in Africa. The trial also reconfirmed the vaccine's safety in one-to-four year old children.

Among infectious diseases, malaria is one of the world's biggest killers. It is estimated that malaria kills between one and three million people in the world's poorest countries every year, and more children in sub-Saharan Africa than any other infectious disease.

Headed from Spain

"Our results demonstrate the feasibility of developing an efficacious vaccine against malaria," wrote Dr. Pedro Alonso, adding that "...malaria vaccines could greatly contribute to reducing the intolerable global burden of this disease." Dr. Alonso, director of the Center for International Health of the Hospital Clinic in Barcelona, Spain, headed this pioneering vaccine trial.

Tested in Mozambique

The double-blind, controlled trial involved over 2,000 children in southern Mozambique. The Minister of Health, Dr. Francisco Songane, said his nation was proud to be a part of such a groundbreaking study. "Malaria is the number one killer of African children. We did this not only for the people of Mozambique, but for the people all over Africa whose health and development suffer greatly from this terrible disease."

Bill & Melinda Gates

"These findings represent a breakthrough in the science of malaria vaccines," offered Dr. Melinda Moree., director of the Malaria Vaccine Initiative. MVI is a global program created to overcome barriers to malaria vaccine development. MVI was started in 1999 with a grant from the Bill & Melinda Gates Foundation and is still funded by it.

The Trial

According to the study, vaccine efficacy against clinical malaria attacks was 30%. Efficacy against primary infection with Plasmodium (P.) falciparum was 45%, and efficacy against severe disease was 58%. P. falciparum is the parasite that causes the greatest number of cases of malaria in Africa.

The Vaccine

The vaccine is directed against the form of the P. falciparum parasite that is injected by mosquitoes. This form is known as the sporozoite. After immunization, antibodies and white blood cells are produced which can prevent the sporozoite from surviving or from further developing in the liver. The vaccine is delivered in a three-dose regimen.

Due to the need for further studies, a licensed malaria vaccine is not expected to be available before 2010, by which time it is projected that half of the world's population, or 3.5 billion people, will be living in areas in which malaria is transmitted.

Sources

1. Primary research report: Alonso PL, and others. Efficacy of the RTS,S/AS02A vaccine against Plasmodium falciparum infection and disease in young African children: randomised controlled trial Lancet 2004; 364: 1411.

2. Accompanying editorial: Van de Perre P and Dedet J-P. Vaccine efficacy: winning a battle (not war) against malaria. Lancet 2004; 364: 1411.

3. Press release: Malaria Vaccine Initiative press release, Oct 15, 2004.