PROVIDENCE, RI — In the early 1990s, seven volunteers in a GlasxosSmithKline lab plunged their hands into boxes filled with hungry, malaria-carrying mosquitoes protected by only a developmental vaccine. When six of the seven volunteers remained 100 percent protected from malaria, the global health world thought that the silver bullet had been found: the RTS,S malaria vaccine.
Even in 2013, the RTS,S malaria vaccine was still on track to be the gold standard of anti-malarial medicine. It passed through animal models and Phases I and II of human clinical trials. However in a large-scale, Phase III clinical trial that included a mass roll out of the vaccine at 11 sites in seven African countries, the RTS,S astounded the medical world one final time by failing to produce even a shadow of what had been achieved in the lab.
The Lancet reported that the vaccine was less than 40 percent effective, even after the intensive four-shot regimen that is required to achieve efficacy. Doctors Without Borders refused to make the RTS,S malaria vaccine a part of its traditional care regimen. When questioned about the efficacy of the vaccine by the New York Times, Dr. Vasee Moorthy of WHO’s vaccine development team could only answer: “We need additional information.”
After 30 years of development, a four-vaccine program that could only ensure a 40 percent chance of malaria protection was not the solution the medical community was hoping for. However, many researchers have refused to give up on the RTS,S malaria vaccine. In a study published in The Lancet in November 2015, some believe that there may be hidden value to the vaccine that many wrote off as a failure.
Researchers Melissa Penny, Robert Verity, Caitlin Bever and Christophe Sauboin, working under the funding of the PATH Malaria Vaccine Initiative and the Bill and Melinda Gates Foundation, argue that RTS,S may have the potential to save millions of lives right now. With no additional biological development, the RTS,S malaria vaccine, even with its low success rate, could place a roadblock in the cycle of malaria transmission.
Using a mathematical model, Penny, Verity, Bever and Sauboin “predict a positive public health impact of the introduction of RTS,S.”
“The absolute impact is substantial with an estimated 116,500 cases of clinical malaria, and 484 deaths averted per 100,000 vaccinated children with a four-dose schedule…This finding translates to roughly one malaria death prevented for every 200 children fully vaccinated.”
According to the U.S. Centers for Disease Control and Prevention, there were 207 million clinical cases of malaria in 2012. Among those cases, 627,000 were fatal—with 91 percent of those deaths occurring in the WHO’s African Region.
Proponents of the RTS,S malaria vaccine are also pushing for the cost-effectiveness of the intervention. The vaccine costs $5 per dose. Although an insecticide-treated bed net can cost a comparable $2.50 to $5, this model predicts that the vaccine may prove more cost effective over a long period of time. Using the public health metric DALYS (or disability-adjusted life years, which gives a metric to the burden of a disease that may not kill, but still severely lessens the quality of life) it is predicted that the vaccine costs $87 per each DALY avoided.
Other traditional methods such as cumulative programs of insecticide treated nets ($27), residual anti-mosquito spraying ($143) and other preventative treatments ($24) may total to a well over $100.
Given these findings, some researchers are still wary that reliance on a vaccine may prevent families from sleeping under bed nets or taking similar appropriate precautions. The New York Times reported that some doctors expressed concern “that parents will assume their children are immune after vaccination and will stop using bed nets and worrying about fevers.”
Dr. Andrea Borsman, chief of WHO’s malaria prevention, added that “a reasonable pilot project target would be proof that 10 percent more children survive when the vaccines are used.”
The findings from The Lancet and the suggestion of future research goals from Dr. Borsman seem to indicate that the medical community isn’t ready to give up on the RTS,S malaria vaccine. It’s far from a panacea, but maybe a step in the right direction.
Sources: Nejm, The Lancet, WHO, The New York Times, Malaria Vaccine, CDC, CDC Foundation