Malaria Prevention Vaccine Edges Closer to Reality

By Gil Ross — Oct 23, 2015
A new vaccine against malaria, a scourge especially in sub-Saharan Africa, shows that a series of three shots offers about 50 percent protection. It's one small-to-medium sized step toward a truly protective malaria vaccine, which would amount to saving many thousands of lives in the near term.

Anopheles mosquite, femaleA new report in the current New England Journal of Medicine is the latest in a series of articles shedding light on the efficacy of RTS,S/AS01, GlaxoSmithKline's experimental malaria vaccine.

In July, the European Medicines Agency s (EMA) Committee for Medicinal Products for Human Use (CHMP) adopted a positive position regarding RTS,S/AS01, the first candidate vaccine for the prevention of malaria to reach this regulatory stage. It is one small-to-medium sized step toward a truly protective malaria vaccine, the holy grail for insect-borne-disease fighters in Africa.

GSK's CEO Andrew Witty said the EMA/CHMP s decision represented "a further important step towards making available for young children the world s first malaria vaccine.

The company noted that it has committed to a not-for-profit price for the vaccine, called Mosquirix, so that, if approved, the price would cover the cost of manufacturing the vaccine together with a return of around five percent, which will be reinvested in R&D for second-generation malaria vaccines, or vaccines against other neglected tropical diseases.

According to the World Health Organization, malaria sickens around 200 million people worldwide each year, and it has killed over 500,000 in 2013, mostly African children and babies under five.

Despite this sizable loss of life, the numbers are actually encouraging since only 10 years ago the estimated death toll was closer to one million. The improved mortality figure comes from more accessible treatments, more accurate and rapid diagnostic tests, preventive efforts (focused on draining mosquito breeding swamps and insecticide-treated bed nets) and the resurgence in many African nations of indoor residual spraying of DDT (IRS). That's despite the needless, ideologically-driven red-tape that has to be overcome to gain approval for such use.

The current NEJM study, authored by a multi-national group of researchers working in several sub-Saharan African nations, was designed to detect variable vaccine-efficacy rates depending on the genetic makeup of the parasite Plasmodium falciparum, the causative microorganism of malaria (transmitted by the bite of the anopheles mosquito).

And indeed, they found such a selective efficacy. Among 4,577 vaccinated infants aged 5-17 months (as compared to 2,335 unvaccinated controls), the researchers found that vaccine efficacy at one year, when the protein genotype was matched well with the vaccine, was 62.7 percent. When the match was absent or poor, efficacy declined to 54.2 percent. Prior studies had shown that protective immunity after three shots waned over a period of several years.

Two things to keep in mind, which are abundantly clear: (1) given the frightful toll of malaria in terms of both morbidity and mortality, even the current vaccine's approximately 50 percent efficacy would save many lives if widespread vaccination is implemented. (2) The march of progress against malaria, including developing an excellent vaccine, is inexorable and inevitable. But the sooner researchers "perfect" such a vaccine, the more lives will be saved.

We have taken note of prior studies of this vaccine (also called Mosquirix) when earlier studies were released: in July and April of this year, in fact.

GSK's research on this crucial medication has been aided by funding from the Bill and Melinda Gates Foundation and the PATH Malaria Vaccine Initiative.