New Vaccine Beats Malaria in Early Trials

Reporting in Science, researchers write of an intravenous vaccine that offered complete protection against malaria in a small clinical trial — but only after five doses. Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases, discusses steps needed to turn this early success into a practical vaccine.

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IRA FLATOW, HOST:

This is SCIENCE FRIDAY, I'm Ira Flatow. For the past 40 years, scientists have known of a way to vaccinate people again malaria. Now I hear you saying wait a second, that can't be true, but you heard me right. There is a way to give people immunity against malaria. The only problem is the vaccine requires subjecting a patient to over 1,000 mosquito bites from mosquitoes treated with radiation in a laboratory. It may be effective, I didn't say it was easy.

But this week, scientists reported an exciting breakthrough. They were able to mimic that 1,000-bite vaccination with just a handful of intravenous shots. They published their work in the journal Science, and here to tell us about it is Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases at NIH in Bethesda. Welcome back, Dr. Fauci, to SCIENCE FRIDAY.

TONY FAUCI: Thank you, Ira, good to be here.

FLATOW: A brief thumbnail, what is malaria, and how does that technique prevent it?

FAUCI: Well, malaria is a disease that's caused by a parasite, the most serious of which is the Plasmodium falciparum. It's transmitted by a mosquito to a human. It has a very complicated life cycle in the mosquito and in the human, and it results in serious disease, anemia, some central nervous system disease, can be renal failure, and it's the cause of a considerable number of deaths worldwide, anywhere from 600,000 to a million deaths per year, mostly in children and mostly in sub-Saharan Africa.

So it's a very serious global health problem.

FLATOW: And this new technique, what does it do?

FAUCI: Well, the technique, as you mentioned, Ira, is to use the malaria parasite itself, one of the components of the replication cycle called the sporozoite, in which you actually get mosquitoes who are infected, irradiate the mosquitoes and take out the component of the malaria parasite that is now weakened, so it can't cause disease, and inject it over a period of multiple injections over a period of time into a normal volunteer, in this case, and then challenge that individual after they've been immunized with a mosquito bite that actually does contain the live malaria.

And the exciting results that were just reported yesterday in Science magazine was that there was a high degree of efficacy for protection against acquisition of malaria in the individuals who were vaccinated with this unusual form of a vaccine.

FLATOW: When you say a high degree, give - what does that mean in lay terms?

FAUCI: Well, what it means is, for example, if you look at essentially all of the comers of the people, let's say 15, 12 of them were protected. If you look at the six people in the study who received the highest dose with the total number of vaccinations being five vaccinations of the highest dose, all six of those individuals were protected, which gives you 100 percent efficacy.

The sobering and cautious news is that's still a relatively small number, Ira. So you don't want to make too many extrapolations from that except to say that the proof of concept is quite impressive because this degree of efficacy has not been seen before. But there's a lot of work to do before this is going to be ready for prime time for sure.

FLATOW: Yeah, and some of that work is that this vaccine is given intravenously, correct?

FAUCI: Well correct, it's given intravenously, which from the standpoint of certain populations, like perhaps tourists or the military, you could use it. But for mass vaccination programs, requiring the insertion of a needle into a vein, particularly in children, is really not particularly feasible.

So you want to build on the proof of concept that the candidate can induce a high degree of protection and then use that to figure out a way how you can administer this vaccine in a more practical or feasible form.

FLATOW: You mean would that be with a regular shot or through some other method you haven't thought of yet?

FAUCI: Well, there are two possibilities, one more likely than the other. One is to develop a device that would be able to get the vaccine into a vein very easily without too much skill or technical difficulty on the part of the administrator. That's less likely. What's more likely is to be able to get this particular candidate and give it in a different route of administration, either subcutaneously or interdermally, namely directly into the skin, but at high enough doses and in a form that would induce the same sort of potent response that the intravenous inoculation gave.

FLATOW: You know, I'm reading a lot of science fiction magazines about medicine, and what they're using in these science fiction magazines are nanoparticles.

FAUCI: Right.

FLATOW: Is that pure science fiction, or is that possible?

FAUCI: No that's - certainly nanoparticles are possible for vaccinations when you're dealing with isolated proteins and molecules that are going to be the vaccine. The important part about this vaccine that we're talking about today, Ira, is that it is essentially injecting the whole parasite into an individual, which is the best way to get the most powerful immunity.

So if you really want to stick with the concept of a live, weakened parasite as your vaccine, then that kind of takes nanoparticles off the table.

FLATOW: And this immunity that they've gotten and that you can expect, do you expect it to last a lifetime?

FAUCI: That's the critical question, because although the degree of efficacy was high, the one remaining question is: What is the durability of this response? If it was challenged a few weeks after the last vaccine that was given to the volunteer, that's not good enough. We want to make sure that you have durability so that when you use it, if it gets to that point where you use it with mass vaccination, you want protection measured in many months and years, not in weeks.

So the next step in the next phase of trials is to determine the durability of the effect and whether or not it could protect against variations of the same sort of malaria parasite.

FLATOW: And this being just in the early stages, then you would have to come up with a better delivery method.

FAUCI: Well, yes, as we mentioned, if you really want to start talking about the feasibility of making this a mass vaccination program, you're going to have to come up with a more feasible way to administer this, not an individual needle-into-a-vein type thing.

FLATOW: Yeah, and you're working on that, too, I'm sure.

FAUCI: Absolutely, absolutely.

FLATOW: All right, Dr. Fauci, thank you, thank you very much for taking time to be with us today.

FAUCI: Good to be with you, Ira.

FLATOW: Have a good weekend.

FAUCI: You, too.

FLATOW: Tony Fauci is director of the National Institute of Allergy and Infectious Diseases at the National Institutes of Health in Bethesda, Maryland.

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