Malaria vaccine study raises questions about effectiveness and dosage

Developers says trials of four doses must go ahead despite research showing three offers little protection after seven years

A baby receives the RTS,S vaccine as part of a trial in Kombewa, western Kenya.
Photograph: Karel Prinsloo/AP

Further doubts about the future of the world’s first malaria vaccine have been raised by research that shows the protection given by three doses declines to almost nothing over seven years.

As the vaccine wears off, the study shows that children living in areas where there is high transmission of the disease end up with more infections than those who have never had a jab – known as the malaria rebound effect. Unvaccinated children – if they survive malaria – develop some natural immunity over the years.

Four doses are known to protect children for longer, but as the protection will still wane, the question that needs to be answered is “are we just kicking the can down the road”? said Prof Philip Bejon, director of the Kemri-Wellcome Trust research programme in Kenya, which conducted the latest study.

In spite of the results of the trial in Kilifi, Kenya, which was published in the New England Journal of Medicine, those behind the development of the vaccine said it must still be rolled out in pilot programmes to thousands of children in Africa by the World Health Organisation as planned. The children will be given four doses rather than three.

The toll in death and disability from malaria among children is so great that the vaccine still could have a role to play in decreasing the number of cases in the early years of life, say those behind the vaccine’s development.

Dr David Kaslow, vice-president for product development at Path, a non-profit international organisation that has been a key player with the pharmaceutical firm GlaxoSmithKline, said up to six doses could be needed to maintain the protective effect.

Since children were getting malaria at a later age, he said, “we need to make sure we also have got immunity during that age period as well, verifying the need for a 4th dose and potentially a 5th and 6th dose”.


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