Problems Found With Glaxo's Malaria Vaccine

By Denise Roland 

LONDON-- GlaxoSmithKline PLC's malaria vaccine, the world's most advanced, loses effectiveness over time, even with a booster shot, according to clinical-trial results published on Friday.

Nonetheless, the scientists who conducted the study said the vaccine still offered a clear benefit to children in sub-Saharan Africa, where the disease is widespread.

Earlier results showed that young children who received three doses of the vaccine in close succession were half as likely to contract malaria in the year following the shots. But a follow-on study published Friday in the Lancet, a medical-research journal, showed that after four years the level of protection dropped to just 36%, despite a fourth dose being given at the 18-month mark.

The effect in infants was weaker still. Babies given the first three shots aged between six and 12 weeks, and a booster later on, were just 26% less likely to contract malaria after three years. They weren't followed up for four years.

The vaccine was also shown to be less effective against severe malaria, the life-threatening form of the disease. Without a booster, neither infants nor young children were protected from this form of the disease after three and four years, respectively. Using the booster made young children 32% less likely to contract severe malaria but made no difference to infants.

The latest results are the final part of a five-year trial on more than 15,000 children across 11 African countries.

Brian Greenwood, professor of clinical tropical medicine at the London School of Hygiene and Tropical Medicine, and one of the scientists involved in the study, said that, despite falling efficacy over time, the vaccine still marked a clear improvement over the status quo.

"Given that there were an estimated 198 million malaria cases in 2013, this level of efficacy potentially translates into millions of cases of malaria in children being prevented," he said.

The Glaxo vaccine is the most advanced inoculation anywhere in the world by at least 10 years. Malaria is notoriously difficult to vaccinate against because the disease is caused by a complex parasite, and it has taken the British drug company nearly three decades to reach this point. Glaxo has said it plans to sell the vaccine at a 5% premium to the manufacturing cost and use the profits to fund further research into vaccines for malaria and other neglected tropical diseases.

Dr. Moncef Slaoui, chairman of global vaccines at Glaxo, said he was "extremely encouraged" by the results. He added: "We might reasonably now expect that the impact of this vaccine candidate, when used with existing interventions, will allow more children to survive the early years which we know is the most dangerous time to be infected with malaria."

Glaxo has already submitted the vaccine to European regulators, based on earlier data, and hopes that the shot could launch as early as next year. The World Health Organization has already indicated that it will recommend the vaccine should it win regulatory approval.

However, WHO officials, also writing in the Lancet, stressed that the vaccine must be funded in such a way as to preserve financial support for other strategies to decrease the spread of the disease, such as the provision of mosquito nets and antimalarial drugs.

Write to Denise Roland at [e-mail]

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