New Malaria Vaccine Glitters; Is it Gold?

Aug 26, 2013 | Jason Hayes | Research & Policy

According to a recent study published in Science magazine, the Maryland-based biotechnology firm Sanaria might have succeeded where many others have failed. Their phase I clinical trials for a malaria vaccine produced 100 percent protective results in six study participants. In the trial, participants who received the vaccine were divided into tiers who received different amounts of the drug via once a month intravenous drips. None of the subjects who received five doses of the vaccine contracted malaria, but 30 percent of the subjects who received four doses did, which suggests the new drug to be dose-dependent. Although the results are recent and only represent the early stages of clinical trials, Sanaria executives told newspapers they hope the vaccine will reach the commercial market in only three to five years—a quick turnaround for a new drug.

Sanaria’s new vaccine seems to many a fantastical response to the tedious and lurking question of whether we can stop mosquito-borne malaria. In 2010, malaria—a disease caused by five species of the parasite genus Plasmodiuminfected over 200 million people through mosquito bites and killed 655,000, most of them children and pregnant women. While malaria is endemic in countries all over the world, over 90 percent of malarial deaths occur in Africa.

In recent years, countries afflicted by malaria have attempted an integrated prevention and control campaign. Public health practitioners try to keep mosquitoes away from people with insecticide treated bed nets, targeted insecticide use, and eliminating mosquito breeding grounds. When someone falls ill, treatment is relatively inexpensive, but recent upticks in anti-malarial drug resistance force doctors and nurses to follow up with patients for weeks or experiment with combination therapies. The new vaccine’s boast of total protection and lack of resistance (though this could easily change in time) make it seem like a magic bullet.

All of the current efforts have had a cumulative effect. Since 2000, the rate of malarial death has fallen by more than 25 percent. However, a sense of urgency still exists. Most likely, a large number of malaria cases go unreported because the non-specific symptoms (fever, aches, malaise) are endured in areas where paying for healthcare, even a few dollars, is an impossibility and access to clinics and practitioners is difficult. Remember, this is a disease that disproportionately affects developing countries in Africa. In underserved areas, getting people bed nets and environmental controls to prevent disease can be both difficult and expensive. In 2010, the international community poured 1.71 billion dollars into malaria control, only to spend 1.81 billion in 2012.

If the frustrations of past methodologies cast a shadow on progress, the new vaccine promises something shiny and hopeful.

The first layer of the new vaccine’s luster is the simple fact that it appears to work; as in, every time. Sanaria is by no means the first company to take a swing at a malaria vaccine, and where name brands like GlaxoSmithKline produced 47 percent or 56 percent protection, the new vaccine claims to stop malaria 100 percent of the time.

The second layer of luster is the improbable and downright cool method Sanaria uses to produce their vaccine. Mosquitoes are fed P. falciparum worms (the most common specie of the parasite) in the worm’s early stage of development—called the sporozoite. The mosquitoes are then exposed to radiation to weaken the parasite while keeping the mosquito alive. Next, scientists conduct microsurgery by hand to remove the weakened parasites from the salivary gland of the mosquito. These surgically removed worms are then sterilized and frozen to be the active ingredient in the vaccine.

Where someone might find tarnish in these coats of sheen and promise is in the numbers. From a study standpoint, there are very few of them. It is difficult to say that forty people in a study in Bethesda, Maryland can be representative of the entire Sub-Saharan population. In addition, such few study subjects raise questions as to whether the results, although statistically significant in the study population, might have been sheer luck. To be clear, this is a common concern for any new vaccine, as the FDA estimates the normal size of a phase I trial to be “between 20 and 80” volunteers.

In addition to small numbers, there are also large numbers to worry about; specifically, cost. If Sanaria’s vaccine makes it to commercial production, there is an unfortunate paradox that malaria may rob the countries that need it most of their ability to pay for the vaccine. Countries with high malaria rates, such as those in Sub-Saharan Africa, grow slower economically than those with low incidence of malaria. While there are undoubtedly myriad reasons for this phenomenon, the absenteeism and loss of human capital to frequent illness and death are all contributing factors. So, how much will it cost to perform surgery on enough mosquito salivary glands to immunize one country? How about a continent?

Stephen Hoffman, the CEO of Sanaria, suggested on a Reddit forum that while the cost will indeed by high for travelers and the military, for poor countries with endemic malaria, “the vaccine will be provided at low cost.” This would be a great step, but it is necessary to remember the logistics involved after buying the vaccine. The six subjects who experienced total immunity to malaria received a treatment of five separate IV drips, which would require personnel trained to deliver IVs, needles, equipment, and cold chain management for enough bags of the drug to give most everyone in a rural, developing country a dose on each of five separate clinic visits. That is no easy task, especially considering the difficulty public health campaigns have already experienced in getting much simpler malaria controls to these areas.

Where Sanaria is now, suspended between criticism and hope, is neither out of the ordinary nor the product of any misinformation. Their initial trial showed promise, but the results are not yet definitive: a normal state of limbo for the three-phase process. However, the promise that there can be a 100 percent protective malaria vaccine is a step by itself. It buffers our hope that one day we will have a definitive prevention mechanism against the tiny parasite.

 

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