Promising results from a recent vaccine clinical trial in Kenya raise new hope in the fight against malaria
The development of a safe and effective malaria vaccine to reduce the intolerable burden that malaria imposes every year could take on new directions thanks to a study published today on Science Translational Medicine. In this study Ogwang et al. demonstrate that 67% protective efficacy against infection with Plasmodium falciparum can be achieved with a promising T cell-inducing vaccination strategy among adults living in a malaria-endemic area in Kenya.
The heterologous prime-boost immunisation regimen developed at the Jenner Institute, United Kingdom uses the recombinant chimpanzee adenovirus 63 (ChAd63) and the modified vaccinia Ankara (MVA), both encoding the malaria antigen ME-TRAP (multiple epitope string and thrombospondin-related adhesion protein). The vaccine stimulates the body’s immune system to produce particular disease-fighting cells (known as T cells) to protect the body from malaria. The phase II clinical trial described in this study was conducted at the Kenya Medical Research Institute (KEMRI) field site located in Junju, Kilifi County, Kenya. Healthy adult male volunteers were randomly allocated to vaccination with either the T cell “inducing vaccine candidates or a control vaccine. Antimalarials were given to clear parasitaemia and frequent blood tests were done to identify new infections with the malaria parasite Plasmodium falciparum. The authors found that the volunteers receiving the T cell-inducing vaccine had a 67% reduction in the risk of malaria infection during 8 weeks of follow-up.
Professor Philip Bejon, The Programme Director KEMRI – Wellcome Trust Research Programme, said: “This promising result will lead to larger scale trials by the Consortium in several populations. This demonstrates clearly the potential of these new viral vectored vaccines and identifies a rapid new means of demonstrating vaccine efficacy against infection in field trials.
Professor Adrian Hill, Director of the Jenner Institute at the University of Oxford said: “This is an exciting and very positive result with this new type of malaria vaccine that targets the parasite in the liver by inducing protective T cell responses. Such high efficacy in this first field trial is encouraging for further testing in children and infants who most need a malaria vaccine.”
This clinical trial was funded by the Malaria Vectored Vaccines Consortium (MVVC), a five year project set up with the aim of integrating capacity-building and networking in the design and conduct of phase I and II clinical trials of viral vectored malaria vaccine candidates in East and West African adults, children, and infants. The overall objective of the project is to develop a safe, effective and affordable malaria vaccine for use by the malaria endemic populations of the world.
This clinical trial follows a series of studies conducted by MVVC partners in sub-Saharan Africa to assess safety, immunogenicity and efficacy of the viral vectored vaccine candidates. Dr Odile Leroy, Executive Director of the European Vaccine Initiative, Germany and coordinator of the MVVC project, said: “This is a great achievement for the MVVC consortium and opens new avenues for innovative and promising vaccine combination strategies.”
The MVVC Consortium consists of the following partners: European Vaccine Initiative, Germany; University of Oxford, United Kingdom; Vienna School of Clinical Research, Austria (until January 2013); ReiThera s.r.l, Italy; Centre National de Recherche et Formation sur le Paludisme, Burkina Faso; Kenya European Vaccine Initiative 2/2 Universitts Klinikum Heidelberg Im Neuenheimer Feld 326 69120 Heidelberg Germany Secretariat: Odile Leroy, Executive Director e-mail: firstname.lastname@example.org, web site: www.euvaccine.eu