Dr Simon Kariuki, Kemri and CDC representative said if the vaccine comes to the market, millions of lives would be saved, especially in malaria-prone areas in Africa.

Invented in 1987, RTS,S triggers the immune system to defend itself against the plasmodium falciparaum, malaria parasite, when it enters the human host’s bloodstream or when the parasite infects the liver cells. This prevents the parasite from maturing and multiplying in the liver.

To stimulate an immune response to malaria parasite, the RTS,S antigen fuses a critical protein with another found in Hepatitis B vaccine. This strengthens the immune response even further and is capable of also preventing Hepatitis B, a chronic liver disease.

After going through two separate phase trials, results found that RTS,S vaccine done in Kenya and Tanzania had a promising safety and tolerability profile, which reduced the risk of episodes of malaria by 53 per cent in children aged between 5 and 17 months over an eight-month follow-up period.

Located in seven African countries with three trial sites, clinical evaluation of RTS,S released in November 2007 showed that after a full vaccination course in infants, it reduced infection by 65 per cent over a three-month period.

It also demonstrated a promising safety and tolerability profile similar to the standard WHO’s expanded program on immunisation vaccines commonly given to infants. A phase three trial for the vaccine is currently underway and if it succeeds, its data will be submitted to regulatory bodies, both international and individual countries to allow it to be introduced in the market.

But the trials may take three to five years before the vaccine finally hits the world market.

Presently, ongoing trials involve a double-blind study in which participants will initially receive three doses of RTS,S or a control vaccine. After 18 months, participants will receive a fourth dose of the vaccine to evaluate the impact of the "booster" dose.

All the 6-12 week old infants in the trial will also receive a standard, licensed vaccine that protects against five common childhood illnesses as recommended by WHO.

"The final stage trial is expected to enroll up to 16,000 children across seven countries in Africa. The majority of malaria deaths in Africa occur in children under the age of five," Kariuki said during a tour of a research facility in Kisumu.

"The other trials involved 4,000 children and more than 50 per cent of the children, as a result of the vaccine, did not go on to have severe malaria, while 30 per cent were completely protected from malaria," Dr Walter Otieno, an RTS,S investigator at Kombewa Research Centre in Kisumu told journalist who attended the launch of Phase III vaccination role-out.

"The Phase III trial is the outcome of a 9-year collaboration between the Path Malaria Vaccine Initiative and GSK Biological, now in partnership with a network of outstanding study centres in Africa, such as the three here in Kenya," said Dr Christian Loucq, director of the Path Malaria Vaccine Initiative.

"If all goes well, we will end up with a vaccine able to save lives and protect many more young children from malaria. We are grateful to the Kenyan Government for allowing this trial to move forward," Loucq added.

Dr Joe Cohen, co-inventor of RTS,S and Vice President of Vaccines for Emerging Diseases and HIV at GlaxoSmithKline (GSK) Biological expressed excitement on the breakthrough and said the moment had special relevance to him following a journey that started in late 1980s when he started working on RTS,S vaccine.