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Will the RTS,S Vaccine Eradicate Malaria?

The development of the RTS,S vaccine brings new hope to the fight against this deadly disease. Its success however, still hinges on support for older methods.
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Blood samples prepared for analysis as a part of malaria trials in Uganda. Photo by Gates Foundation

Kampala, Uganda:

It is a heady time to be fighting malaria. The promise of a potential vaccine has energised public health workers, who now find themselves on the cusp of loosening the disease’s deadly grip on the developing world.

There were 216 million cases of malaria in 2010, according to the World Health Organization (WHO), and as many as 655,000 people died of the disease that year – the majority of them children and most of them in sub-Saharan Africa. Until recently, the best bet for fighting the spread of the mosquito-borne disease was distributing insecticide-treated bed nets and spraying insecticides indoors. That still left thousands exposed to malaria, some with severe cases and too far from health centres to access treatment in time.

In 2007, Melinda Gates – a co-chair of the Gates Foundation – dropped something of a bombshell on the international community: setting a goal of completely eradicating the disease. She recognised at the time that it was an “audacious” target.

Then, last November, The New England Journal of Medicine released the first results from a trial of a malaria vaccine, called RTS,S, that showed more than a 55% reduction in malaria cases for children five to 17 months old over a one-year period. The same study showed RTS,S reduced by almost half the number of severe cases of malaria in the same age group.

“That’s a major breakthrough,” says Dr. David Kaslow, the director of the PATH Malaria Vaccine Initiative (MVI), which is driving the development of RTS,S, alongside its producers, GlaxoSmithKline. The vaccine could have “a huge impact on millions and millions of kids who suffer from malaria” and move the public health community closer to the Gates’ goal of complete eradication.

Testing ... 1,2,3

The current RTS,S trial – the third and final test phase of the vaccine – is still ongoing at 11 trial sites in seven African countries. Researchers are testing its effectiveness in children of different ages. But if all goes well and the vaccine gets the sign-off from international regulatory organisations like the WHO, Kaslow says RTS,S could be ready for market by 2015.

Dr. Salim Abdulla is the chief executive director of the Ifakara Health Institute (IHI), based in Dar es Salaam. IHI is running one of the testing sites in Bagamoyo, Tanzania. He says a vaccine – even a partially effective one – could be critical in a place like Tanzania, where healthcare in some rural areas can be hard to come by.

“There is still a proportion of patients who are far from healthcare [and] do not get prompt care,” he says. “For this reason, a preventive measure against the disease will have a much bigger impact than just focusing our efforts on treating the cases that occur.” “We were able to deliver vaccines to the most remote places in Africa,” Abdulla notes. “This is what gives us hope. That we have a tool that we can take to the children across Africa.”

He says it is much easier to facilitate routine childhood vaccinations in far-flung areas, than to treat cases of malaria as they arise. One of the elements of a previous phase of the RTS,S trial, he says, was determining that the malaria vaccine could be safely given alongside other standard childhood vaccines, like polio and the measles.

Creating even a partially effective vaccine against malaria is something of a scientific breakthrough, Kaslow says. It’s the first effective vaccine against a parasite, which he describes as “an order of complexity higher” than viruses, like the flu, or bacteria.

Side effects of a cure

The vaccine will not provide injected infants with lifetime immunity to the disease, though it could help get them through the years when malaria can be most deadly. Without it, people who survive repeated exposure to malaria begin to develop a natural immunity to the disease. Kaslow said one of the aspects of the vaccine they are still testing is whether it will still allow children to begin developing that natural immunity.

RTS,S has been kicking around for 25 years since a version was first created by Glaxo. MVI, with funding from the Gates Foundation, has formed a public-private partnership with Glaxo to develop the vaccine for use among infants and children in sub-Saharan Africa.

One of the missions of the partnership is to bring governments into the process now, during the testing period, so that when the vaccine is ready for launch, they can have policies and protocols in place to facilitate distribution as quickly as possible.

At over 50% effectiveness, the vaccine isn’t perfect. Kaslow calls it a “great place to build off of”. But even if universal rollout is achieved in endemic malaria regions, there will still be a need for bed nets, for spraying and for well-equipped treatment facilities for children and adults who manage to contract malaria. So research continues into a variety of other ideas for controlling – and ultimately eradicating – the disease.

Sham Lal is a research assistant for the ACT Consortium out of the London School of Hygiene & Tropical Medicine. ACT stands for artemisinin-based combination therapy, which is the most effective treatment for malaria. With 16 studies in nine countries, the consortium is researching the most effective way to deliver the drug while also trying to guard against drug resistance.

One of the major problems in malaria treatment is that without a well-developed health infrastructure in rural communities, health workers diagnose patients based on signs and symptoms of malaria, which can often look like the flu or other common illnesses. That can lead to an over-diagnosis of malaria and an over-prescription of medicine, which in turn can facilitate drug resistance. Inappropriate treatment of presumed malaria can delay a patient’s trip to the doctor to get treated for the real problem.

At one of Lal’s sites in western Uganda, his team is trying to determine if by using rapid diagnostic tests (RDTs), health workers can quickly determine which children actually have malaria and get them on treatment within 24 hours, while not over-prescribing ACT. He says the research should be out by the end of the year.

The key to eradication

The consortium, which is also funded by the Gates Foundation, was started in 2007 with “this idea in mind that this drug coupled with these ideas of eradication could help with country’s control programmes”, Lal says. There is recognition that until a 100% effective vaccine comes along, there will still be a need to deliver and safeguard the treatments that do still exist.

The key, according to Kaslow, is to keep resources and research focused on malaria until it is entirely eradicated. That is why there is a need for groups like the ACT Consortium. MVI and IHI also have other studies in the pipeline.

For a donor community and public who are often looking for the latest flavor-of-the-month issue on which to focus, keeping attention on malaria could be difficult, especially if there is quick success with RTS,S and malaria cases start to drop rapidly.

“As we drive the burden of malaria down, there will be a temptation to back off,” Kaslow says. “That would be a big mistake, particularly with something like malaria. It will come back with a vengeance.”

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Comments

An interesting article, but the key to fighting malaria will always be tackling poverty and improving education, especially among women.  The "over 50%" rating is actually around 52-56, saying it's imperfect is an understatement.  I'm all for biomedical research, but it only treats one symptom (malaria) of the real problem (poverty).  Good, informative read though.  

Hi Chris - Thanks for commenting. Agreed that poverty is one of the driving issues of the continued presence of malaria, especially in the parts of East Africa I report from and achieving complete eradication will require looking at the host of underlying factors.