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London School of Hygiene & Tropical Medicine Malaria Centre

Malaria research in immunology and vaccination

Phase III Trial of RTS,S/AS01 Malaria Vaccine Candidate in African Children.

LSHTM investigators:
Daniel Chandramohan, Chris Drakeley, Brian Greenwood, Seth Owusu-Agyei & David Schellenberg.
External collaborators:
The RTS,S Clinical Trials Partnership.
Funding body:
PATH Malaria Vaccine Initiative.

RTS,S/AS01 is the most advanced malaria vaccine candidate which has progressed through phase II clinical trials to a multi-centre phase III study.

This is being conducted by a broad partnership involving researchers from 11 research centres in 7 countries in sub-Saharan Africa, their associated northern partners, GSK and the Malaria Vaccine Initiative at PATH. The study has recruited 15,460 children in two age categories – 6-12 weeks and 5-17 months old at the time of dose 1 – and randomised them to receive either RTS,S or a comparator vaccine. The primary endpoint is efficacy against clinical malaria and secondary endpoints include efficacy against severe disease, efficacy in different transmission settings and the role of a booster dose.

Results of the primary endpoint analysis during 12 months of follow-up in the 5-17 month age category were published in 2011. RTS,S efficacy against clinical malaria was 55.8% (97.5% CI, 50.6 to 60.4), with 0.55 episodes of clinical malaria per person-year in the control group and 0.32 episodes per person-year in RTS,S recipients). Efficacy against severe malaria was 45.1% (95% CI, 23.8 to 60.5). Overall, serious adverse events occurred with a similar frequency in the two study groups. The rate of generalized convulsive seizures after RTS,S/AS01 was 1.04 per 1000 doses (95% CI, 0.62 to 1.64). The primary endpoint for children in the younger age category will be evaluated towards the end of 2012, and complete trial results are expected to be available for review by policy makers in 2015.