Possible Breakthrough in Battle to Eradicate Malaria

The most ambitious attempt to engineer a vaccine against malaria has cleared another key hurdle, with tests among African babies showing the prototype to be safe and highly protective, a study released this week said.

Known by its lab name of RTS,S the prototype is raising high hopes of the first vaccine shield against a disease that claims more than a million lives a year – 800,000 of them African children aged under five – and sickens hundreds of millions more.

RTS,S was first formulated two decades ago and has been in cautiously widening trials since 1992.

The new test was conducted among 214 infants in villages in rural Mozambique, 50 kilometers north of the town of Manhica, where malaria is endemic.

The babies were randomly assigned to one of two groups.

At the ages of 10 weeks, 14 weeks and 18 weeks, they either received RTS,S or a standard hepatitis B vaccine called Engerix-B, which was used as a “control,” or comparison for seeing how the prototype worked.

In addition to these vaccines, the babies also received routine immunisation jabs at the ages of eight, 12 and 16 weeks.

Infants who received RTS,S were 65 percent less at risk of contracting malaria compared with their control counterparts.

In a previous trial in 2004 – conducted amongst 2,022 Mozambican children aged one to four rather than among babies – the vaccine was 45-percent effective.

In both trials, the vaccine was safe and there were no adverse effects from it.

In the latest test, four deaths occurred in both groups and there were 61 cases of sickness. None of these fatalities or illnesses, though, could be attributed to either vaccine, according to the paper, which is published online on Wednesday by the British health journal The Lancet.

The investigators say the outcome gives a “strong and positive signal” for launching Phase III trials – the biggest but final stage in the exhausting process of testing a vaccine for safety and effectiveness.

RTS,S comprises proteins taken from the early development stage of the Plasmodium falciparum parasite which causes malaria.

These proteins have been fused into a tried-and-tested hepatitis B vaccine.

The double goal is to protect the individual against hepatitis and also prime the immune system to recognise P. falciparum after the parasite is transmitted in a mosquito bite and travels to the liver, where it matures and proliferates.

The investigators add a small caveat about the trial, pointing out that the homes of all the babies who took part in the test were provided with free insecticide-treated bednets and were sprayed twice with insecticide.

“The future use and deployment of a malaria vaccine should be seen in the context of comprehensive malaria control programs,” they caution.

The vaccine was developed by GlaxoSmithKline Biologicals of Belgium, which says it has invested more than 300 million dollars in the venture.

Its researchers took part in the trial alongside counterparts from the University of Barcelona, Spain, from Mozambique’s Health Ministry and Eduardo Mondlane University, and from the PATH Malaria Vaccine Initiative (MVI) in Maryland.

The Bill and Melinda Gates Foundation donated US$107 million to MVI in 2005.

If further evaluations give the green light, “a Phase III trial, involving 16,000 children in seven African countries, could start in 2008,” MVI’s Christian Loucq said.

“If all goes well, the vaccine would be submitted for approval by the European health authorities in 2011.”

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