Results from a large-scale Phase III African trial of an experimental malaria vaccine by GlaxoSmithKline (GSK) shows that it continued to protect young children up to 18 months after vaccination.

Malaria kills 660,000 people a year, mostly children living in sub-Saharan Africa.

The news about the trial results raises hopes that the first protective shot against the mosquito-borne disease will be available in 2 years.

GSK says the data from the trial supports their plan to apply to the European Medicines Agency (EMA) for regulatory approval in 2014.

The World Health Organization (WHO) says if the vaccine candidate gets a positive scientific opinion from the EMA, then it is possible that a policy to recommend the vaccine will be issued as early as 2015.

The latest trial result showed that over 18 months of follow-up, GSK’s candidate malaria vaccine RTS,S reduced cases of clinical malaria by 46% in young children aged 5-17 months after first vaccination, compared with children immunized with a control vaccine. Babies aged 6-12 weeks after first vaccination had 27% fewer cases of clinical malaria.

Comparing the 28-month results with the trial’s results at 12 months, shows that the vaccine’s overall efficacy declines with time. At the 12-month point, the efficacy was 56% reduction in cases in the 5-17 month age group and 31% in the 6-12 week age group.

The vaccine is continuing to show an “an acceptable safety and tolerability profile” during the 18-month follow-up, says GSK.

RTS,S works by triggering the immune system to defend against the malaria parasite when it first enters the human bloodstream, or when it infects liver cells.

The result is the parasite stops infecting, maturing and multiplying in the liver, thus preventing the next stage where it leaves the liver and goes back into the bloodstream to infect red blood cells, causing disease.

In the Phase III trial, the vaccine has been delivered in three doses, 1 month apart.

Next year, the trial investigators expect to reveal more data from 32 months of follow-up, plus the impact of a fourth booster dose that is given 18 months after the initial three doses of RTS,S.

Eleven research centers in seven African countries are conducting the trial, together with GSK and the PATH Malaria Vaccine Initiative (MVI), which receives funding from the Bill & Melinda Gates Foundation.

Dr. Halidou Tinto, Principal Investigator from the Nanoro, Burkina Faso, trial site and member of the committee overseeing the Phase III trial, says:

Many millions of malaria cases fill the wards of our hospitals. Progress is being made with bed nets and other measures, but we need more tools to battle this terrible disease.”

Dr. Tinto says it appears that the vaccine has the potential to make a significant public health impact. Preventing significant numbers of malaria cases means a community will have fewer hospital beds filled with sick children, and:

“Families would lose less time and money caring for these children and have more time for work or other activities. And of course the children themselves would reap the benefits of better health.”

In an August 2013 issue of Science, researchers reporting results of an early-stage clinical trial of an unusual experimental malaria vaccine say it may provide 100% protection against malaria infection in healthy adults.