For the first time in history, scientists have completed successful human trials of a malaria vaccine that provides 100 per cent protection against the often fatal disease.
Currently, we have no truly effective method of protecting against malaria. Even the World Health Organisation had only set their sights on a vaccine with an 80% efficacy rate — and they weren’t planning to have that until 2025. Because before today, according to Anthony Fauci, director of the US National Institute of Allergy and Infectious Diseases in Bethesda, Maryland, “we have not even gotten anywhere near that level of efficacy.” But this newest incarnation has surpassed everything we thought possible.
Called PfSPZ, the vaccine is made from weakened sporozoites (SPZ), the form of the malarial parasite Plasmodium falciparum (Pf) when it’s in its initial infectious state. Even though the parasite is weakened, it’s in its whole form, thus invoking an immune response. The six human subjects that were given five intravenous doses of PfSPZ were 100% protected when they were later bitten by infectious mosquitoes — five of the six unvaccinated control participants and three of the nine people only given four doses went on to develop malaria.
Previously, most of the malaria vaccines being experimented with only used a few of the parasite’s proteins. Stephen Hoffman, head of the Maryland developing firm Sanaria, decided to test a vaccine using the whole sporozoite after researching past experiments going back to the 1970s in which strong, long-lived protection from malaria resulted from volunteers being exposed to thousands of bites from irradiated infected mosquitoes. Stefan Kappe, a malaria researcher at the Seattle Biomedical Research Institute in Washington, tells Nature:
The trial results constitute the most important advance in malaria vaccine development since the first demonstration of protection with radiation attenuated sporozoite immunization by mosquito bite in the 70s. This is a pivotal success.
But part of the reason it’s taken so long to get to this point is that the process of actually making the vaccine is incredibly difficult and complex. First Sanaria had to raise mosquitoes in sterile conditions “on an industrial scale.” He would feed them blood that had been infected with the malaria parasite and then exposed to radiation to so that the parasite would weaken. That way, the body would recognise its presence without being infected with the actual disease.
Next, billions of these parasites were harvested from the mosquitoes’ salivary glands, purified, and cryopreserved. And while all this was happening, most researchers in the field were expecting him to fail. They didn’t think it would be possible to mass-produce this parasite in a way that passed the highly strict quality and safety standards that human medicine must undergo. And now, as Fauci mentioned to Nature, “To my amazement, Hoffman did it.”
Now, the trial is going to need to be repeated and over a much wider range of participants in the regions where malaria is most rampant. This way, scientists will be able to determine if it’s actually effective against strains different from that used in the vaccine, as well as how its effects might vary according to age, gender, etc. From what we’ve seen so far, though, we have every reason to hope that we may be on our way to making malaria a thing of the past. [Nature]