Experts are recommending that a malaria vaccine progress to Phase 3 trials following the successful trial of the RTS, S/AS01E malaria vaccine among 5-17 month old children in Korogwe, Tanzania and coastal Kenya, which is reported in the New England Journal of Medicine (NEJM).
In a separate paper, which also appears in the online journal, the findings are presented of the first co-administration of the RTS, S/AS02 malaria vaccine through the WHO Expanded Program on Immunization (EPI) in infants living in an area of perennial transmission in Tanzania.
The RTS,S vaccine was invented, developed and manufactured by GlaxoSmithKline Biologicals, an active partner and the sponsor of the trials. Funding and technical support for the studies was provided by the PATH Malaria Vaccine Initiative (MVI) through a grant provided by the Bill & Melinda Gates Foundation.
Malaria persists as a major public health problem, and new tools for control of the disease are needed to facilitate the current renewed commitment for its control or elimination.
The first paper reports on the findings of a double-blind randomized trial of a novel formulation of the malaria candidate vaccine (RTS/S/AS01E, which was invented, developed and manufactured by GSK Biologicals) conducted in Tanzania and Kenya by a team of international experts. 894 children aged between 5 and 17 months, a target population for vaccine licensure, were treated and followed up between 4.5 and 10 months.
A team from the London School of Hygiene & Tropical Medicine (LSHTM) including Lorenz von Seidlein, Reader in Clinical Epidemiology, Chris Drakeley, Senior Lecturer, clinical trials manager Jayne Gould, and Eleanor Riley, Professor of Immunology, all in the Department of Infectious Diseases, led the work in Korogwe, Tanzania in collaboration with Dr John Lusingu and colleagues from the Tanzanian National Institute for Medical Research. Dr Philip Bejon of the Kenya Medical Research Institute (KEMRI) Wellcome Collaborative Research Programme and the Centre for Tropical Medicine, University of Oxford, led similar efforts in Kilifi, Kenya.
Among the 835 children who were vaccinated according to protocol, estimated vaccine efficacy against clinical malaria was 53%. A strong immune response was detected, and the vaccine was safe. There were fewer serious adverse events among the RTS,S/AS01E vaccine recipients.
Based on the findings, the authors recommend a multi-centre Phase 3 trial of the RTS, S vaccine which will lead to an application for licensure if these findings are confirmed.
In a second paper, a team including David Schellenberg, Professor of Malaria & International Health at LSHTM, reports that a slightly different formulation of the vaccine candidate, which is being developed for delivery through the EPI, has a promising safety profile and does not react adversely with other antigens being administered as part of the immunization programme. The vaccine also showed a reduction in the incidence of malaria infection by 65%, a welcome but unexpected finding given that this was primarily designed as a safety and immunogenicity trial with only 340 infants enrolled.
Chris Drakeley comments: 'These two important papers add to the data on RTS,S, making a strong case for moving forward to large-scale vaccination in phase 3 trials. The formulation of RTS,S with the ASO1E adjuvant has improved vaccine efficacy considerably. Testing the vaccine in a broad range of epidemiological settings will show if it is suitable for inclusion in routine vaccination programmes throughout sub-Saharan Africa'.