After decades of work, a malaria vaccine (search) may be within reach. Such a vaccine could eventually save millions of lives around the world.

Every year, malaria kills more than 1 million people and makes 500 million people sick. Although the disease is rare in much of the world, it's deadly in many developing countries in tropical areas. If the world's population grows as expected, almost 3.5 billion people will be living in malaria-affected areas by the year 2010.

Anti-malaria drugs (search) were once highly effective, but emerging resistance may be diminishing their effectiveness.

Several potential malaria vaccines are in development. Researchers recently tested one of the most advanced malaria vaccines in the southern African nation of Mozambique.

Malaria Vaccine Decreases Cases, Severity

The malaria vaccine -- made by GlaxoSmithKlineBio (search), a WebMD sponsor -- combats the malaria-causing parasite called Plasmodium falciparum (search).

Pedro Alonso, MD, of University of Barcelona in Spain, worked with colleagues to see whether the malaria vaccine protected children from malaria.

They studied more than 1,600 children aged 1-4 years old in two areas of Mozambique. The kids receive either the malaria vaccine or an unrelated vaccine.

The vaccines were given in three doses by injection to the arm. The researchers, who made sure the families didn't know which vaccine they got, monitored the children for six months. Any cases of malaria detected during that time were immediately treated.

The children who got the malaria vaccine had 30 percent fewer malaria episodes than the comparison group. The malaria vaccine also lowered the number of severe malaria cases by about 58 percent.

The malaria vaccine may have worked even better at protecting the youngest participants, who are the most vulnerable to the disease. Children younger than 24 months who received the malaria vaccine were 77 percent less likely to have severe malaria during the study.

The malaria vaccine did not totally prevent malaria. Instead, it made it less common and less deadly.

None of the children who received the malaria vaccine died of malaria, which claimed the lives of four children in the comparison group.

Malaria Vaccine Few Years Away

The malaria vaccine appeared to be safe. Side effects were mostly mild or moderate, lasting only a short time and including irritability, drowsiness and soreness or pain at the injection site.

Participants will be monitored to gauge the malaria vaccine's long-term safety and effectiveness. Meanwhile, the malaria vaccine could be available by 2010, say Philippe Van de Perre of France's University of Montpellier, and colleagues in an editorial.

The study and editorial both appear in the Oct. 16 issue of The Lancet.

By Miranda Hitti; reviewed by Michael W. Smith, MD

SOURCES: Alonso, P. The Lancet, Oct. 16, 2004; vol 364: pp 1411-1420. Van de Perre, P., The Lancet, Oct. 16, 2004; vol 364: pp 1380-1382. News release, The Lancet. Associated Press.