By MAJ Jason A. Regules and COL Christian F. Ockenhouse
Critical field-site testing for the current Phase III study is ongoing in western Kenya at the U.S. Army Medical Research Unit-Kenya (USAMRU-K), an overseas laboratory of the Walter Reed Army Institute of Research. Here, Kenyan healthcare workers participate in malaria microscopy training conducted by USAMRU-K. (U.S. Army photo by U.S. Army Africa.)
The Walter Reed Army Institute of Research (WRAIR) and public-private partners recently received recognition from Time magazine for the development of the RTS,S malaria vaccine candidate, when Time called the vaccine the second most momentous medical breakthrough of 2011.
Malaria is a major worldwide problem that is endemic to regions of strategic importance to the United States, such as tropical Africa, Asia, Oceania, and Latin America. There are 300 million cases of malaria annually, with an estimated 1 million deaths. Infected pregnant women and children are prone to severe disease.
U.S. military personnel and others from non-endemic regions are also extremely susceptible to severe disease and/or death from malaria. The threat has a substantial impact on deployed U.S. military forces in malaria-endemic areas. Malaria has been a leading cause of non-battle injuries in every major U.S. conflict, including the Revolutionary War, the Civil War, World Wars I and II, the Korean Conflict, and Vietnam. Recent outbreaks have been reported in U.S. and allied troops returning from locations such as Somalia, South Korea, Liberia, French Guiana, Sierra Leone, Cote d’Ivoire, and Afghanistan.
The trial to develop the RTS,S vaccine was conducted in 15,460 infants and children at 11 study sites across Africa. It demonstrated that the vaccine was 56 percent effective in protecting children 5 to 17 months old from malaria infection and was 47 percent effective in preventing severe cases of malaria. The final data will be available in 2014 when the trial is completed. The RTS,S Phase III field trial is the largest malaria vaccine trial ever conducted.
The RTS,S vaccine, the most advanced malaria vaccine ever created, represents over two decades of collaboration between WRAIR and key civilian partners, such as GlaxoSmithKline PLC (GSK). The WRAIR Malaria Vaccine Development Program has executed clinical testing of more than a dozen prototypes, leading up to the RTS,S particle. Using the WRAIR malaria challenge model, whereby humans are experimentally inoculated with malaria after vaccination, the U.S. Army conducted the first proof-of-concept clinical trial demonstrating the protective efficacy of RTS,S.
U.S. Army malaria vaccine researchers also participated in the first RTS,S clinical trial in Africa. Multiple clinical trials have been executed at WRAIR to optimize vaccine presentation and safety. Critical field-site testing for the current Phase III study is ongoing in western Kenya at the U.S. Army Medical Research Unit-Kenya, an overseas laboratory of WRAIR.
Research on the next-generation vaccine has already begun. Although the current RTS,S formulation protects against a very advanced parasite, individuals vaccinated with it would still be at risk of malaria after prolonged exposure because the vaccine is just above 50 percent effective; a military malaria vaccine must achieve 80 percent or greater efficacy to protect our warfighters.
As it continues to develop and test improvements to the RTS,S malaria vaccine in the clinic, WRAIR is joining with public-private partners such as GSK, Crucell NV, and the nonprofit PATH Malaria Vaccine Initiative in an innovative trial to achieve greater efficacy by “boosting” the immune response to the RTS,S particle after “priming” the immune system with a combination of weakened virus and malaria parasite surface protein. The study volunteers will be malaria-naive adults, a target population that parallels deployable U.S. military personnel.
As a scientific leader in the field, the U.S. military malaria vaccine community is uniquely positioned to make a critical contribution at the crossroads of force protection and global public health. Given an increasing trend in global resistance to malaria drugs, the worldwide sickness, death toll, and cost of malaria, and the difficult task of protecting the fighting force, the development of an optimal malaria vaccine is a clear priority for the U.S. military medical research effort and our global health partners.
For more information, visit http://www.tatrc.org/conferences/ata_2011/abstract/Proctor_abstract.html.
- MAJ JASON A. REGULES is a Clinical Investigator and Chief of the Parasite Culture Lab at the WRAIR Malaria Vaccine Branch, on the staff at the Walter Reed National Military Medical Center Infectious Diseases Service, and an Assistant Professor at the Uniformed Services University of the Health Sciences (USUHS). He holds a B.S. in neurobiology, physiology, and behavior from the University of California at Davis and an M.D. from the USUHS. He completed his internship, residency, and fellowship at Brooke Army Medical Center in San Antonio, TX, and is a board-certified physician in both internal medicine and infectious diseases.
- COL CHRISTIAN F. OCKENHOUSE is Director of the WRAIR Malaria Vaccine Branch. He holds a B.S. from Wheaton College, an MSPH from the Tulane University School of Public Health and Tropical Medicine, a Ph.D. in immunology and molecular parasitology from the Sackler Institute of Graduate Biomedical Science, and an M.D. from the Medical College of Pennsylvania. He completed his internship, residency, and fellowship at Walter Reed Army Medical Center in Washington, DC, and is a board-certified physician in both internal medicine and infectious diseases.
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