And now for the question from the dark side....

If this vaccine is 50-65% effective, that would mean that for one in three children who get the treatment, it will not work and worse yet, the malaria which survives the effort to treat it will, ergo, gain increased resistance to the vaccine and gradually grow stronger and begin to eat into the 50-65% effective rate...will it not?

Dweb: here is a case where I think anthropogenics won't make the problem worse--there will less total infections and this will decrease the the probability of mutation? Some geneticist will surely weigh in. I would think that there will be greater resistence to malaria
in the children and their offspring who survive due to the vaccine. The converse would be true of those the vaccine can't help to reach maturity. Something has to be done--one of the great plagues of Africa that stifles progress.

Here, here! I lived in the Gambia, and the saddest part of that experience was the realization that malaria kills kids. The only immunity is through mother's milk, and it turns out that this is sporadic at best. I knew the mothers and fathers of more than one child that died.

Three cheers to anyone or anything that can cut that number: mefloquin, nets or vaccines!

As I stepped away, I realized that the saying probably makes more sense as "Hear, hear." Though I don't know which one is correct and I don't have the energy to check Google... which is on my toolbar, an inch and a half away. Good night, all, and kudos to the vaccine nevertheless.

As I recall, when it came to AIDS in Africa, GW was against the use of condoms because they're not 100% effective. My guess is that condoms are more effective at preventing the spread of STDs than this vaccine will be.... its a good thing GW is leaving office or this vaccine would never get used.

Indeed this is good news. Let's hope that the new medicine cannot be smoked, however.

As much as I would like to take hope from this news, experience makes me cautious. Since 1988, when I spent two years in West Africa, I have been reading about a 'breakthrough' every few years. If this is still in the news a year from now, that may mean something. Even then, with only a 50% benefit initially I have to wonder how long before malaria develops resistance.

Keep in mind that things like vaccines have both an individual effect and a community effect.

To take an extreme example, if the malaria vaccine was 100% effective, but only 50% of kids in a highly endemic village got their jabs, the other 50% of kids would still be "protected" to some extent, because overall transmission is reduced (this would be a "positive externality" to the econ people).

Could the malaria parasites (there are 4 major types of malaria) develop resistance over time? No doubt. But this is why you've got to approach the problem from several angles: vaccines, treatment, use of insecticide treated bed nets, indoor residual spraying, etc.

If your targeting is good - you throw all you've got at the communities where malaria is most endemic - you can damn near wipe it out in those communities.

But, yeah, if you're not on your toes, malaria will always bounce back, particularly in areas where there is lots of migrant labor activity.

Hard to say about the long-run effect of evolution (shhh) of resistance, but in the short run, the effect would surely be a huge reduction in the number of cases.

First, ineffectiveness of a vaccine is not by any means necessarily due to resistance of the target pathogen; rather, it can be due to failure of the patient's immune system to respond. Thus the primary evolutionary effect is more likely to be an increase in the population of humans who are responsive to the vaccine (assuming it's an inheritable trait) rather than in the population of pathogens somehow resistant to it.

Secondly, even if ineffectiveness is due to the resistance of pathogens, for such pathogens to spread would require direct or indirect human-to-human transmission of that subset of pathogens. But that subset is only a fraction of the total set of pathogens, the (presumably unchanged) rate of human-to-human spread of which would be markedly reduced by the reduction in incidence of malaria due to the vaccine. So it would be a subset of a much reduced number, and so certainly smaller in the short run.

The long-run effect would depend on the balance various parameters, of course, including importantly the underlying mutation rate of the malaria pathogen, but at first glance, it's a small risk compared to the benefit.

And now from the rally dark side: Who is going to own this drug for "lisencing" and how are these poor countries going to afford it?

If this vaccine is 50-65% effective, that would mean that for one in three children who get the treatment, it will not work and worse yet, the malaria which survives the effort to treat it will, ergo, gain increased resistance to the vaccine and gradually grow stronger and begin to eat into the 50-65% effective rate...will it not?

Given the nature of the virus' vector, no. not necessarily. Reducing its incidence will mean that fewer mosquitoes bite infected people, which will reduce its incidence further. It may be the effect will be to select for less virulent strains, as is the effect of nets and screens. (Nets and screens prevent the most hard-hit, those infected with the most virulent strains, from passing it on.)

I've had malaria. It's the sickest I've ever been. Horrible.

bleh--

Pretty sure there is no human to human transmission.

There is a treatment for malaria that is highly effective: artemisinin-based combination therapies. The current problems are twofold. 1)People take artemisinin even when they do not have malaria and in so doing develop resistance to its beneficial effects. 2)It is too expensive to be used on the large scale that is needed. The latter problem is being addressed by large pharmaceutical companies, the Gates Foundation, and sovereign funds. The incidence of malaria is going to start dropping dramatically over the next decade and hopefully will stop being the massive killer it is.

Generally speaking, in the vaccine world efficacy rates under 90% would be considered a failure. Malaria is different for a number of reasons and this is why this trial is so encouraging. Note that the parasite that causes the disease is not a virus or a bacteria and isn't transmitted person-to-person but through the bite of an intermediate host, a carrier mosquito. The herd immunity effect noted above where vaccinating 50% of the kids 'protects' the other 50%) doesn't have the same dynamics in this case as you would expect to see with a virus spread from me to you directly.

Being able to establish some level of immunity to the parasite has been difficult mostly because of the parasite's ability to change it's coat and evade immune recognition in the infected host and the fact that this vaccine has some protection is fantastic. Getting to the point above that an ineffective vaccine will encourage selection of mutant is less of a consideration with the malaria parasite because individual vaccine failure probably wasn't caused by mutant parasites, but by a more general failure of the individuals immune system to block infection. Selection pressure on the parasite in this context is expected to be less than you would get with the influenza virus for instance.

Last, this is good news because it represents success with what is widely viewed as pretty primitive technology. The basic vaccine was developed 20 years ago, with a formulation boost about 10 years ago. The state of the vaccine art has progressed considerably since this formulation entered clinical trials and those improvements are working their way through the pipeline now. It should only get better from here on out.

Overall, a pretty encouraging advance.

jayackroyd: You're right, of course, there is no human to human transmission of malaria.

But movement of malaria-infected humans from one place to another can increase incidence in areas where malaria previously had been "tackled" to some extent.

I've seen this just last month...communities in a province with (until fairly recently) low-ish levels of malaria prevalence are seeing upswings in malaria because of the in-migration of workers from more endemic communities, who bring the parasite with them in their bloodstreams.

Local mozzies feed on the migrants, which kick starts a new cycle of infection.

Bigsky in AZ:

Oops...thanks for reminding me that herd immunity doesn't work for malaria in the same way as for bugs that are transmitted human to human. My bad.

How is curing malaria going to make their lives better ? Not to sound crass, but aren't the populations most effected by this disease in desperate need of food and clean water ? Isn't this just going to change the cause of death from one disease to another, from malaria to dysentery to aids to eventual starvation.

Something that might help to clarify the comments about "resistance": a vaccine is not an antibiotic; it doesn't work by being toxic to the disease-causing organism, or by interfering with some specific part of its life cycle. It just gives the immune system a heads-up, teaching your body to recognize the dangerous organism before you actually get infected. The organism could still evolve to become more aggressive against your normal defenses, but it could do that anyway; in other words, the selective pressure is from the human immune system, not from the vaccine.

Also: ScottW, there are a lot of problems in the world, but what you just said is nihilist nonsense. If you really care, it's easy to learn something about the various problems that affect different parts of Africa, rather than just assuming it's all one big hellhole.

dweb might be right, and the scientists will surely follow the story.

However, if the vaccine works as well when distributed to the population, then huge numbers of people will be much healthier for much longer periods of time, which will enable them to solve other problems in their societies.

The vaccine will, in fact, enable them to make sufficient wealth to adopt the other anti-malarial strategies such as medications and mosquito netting.

Hilzoy, thanks again for a good post. You are a bright light.

ScottW,
Gosh no. I'm echoing Hob here, but first, we solve problems one thing at a time. Second, malaria is truly truly awful. My experience with it was the same as jack's upthread - it was the sickest I've ever been, so lessening that is good. Third, you have an exaggerated view of third-world misery - some places / situations are that bad, but many are much better than that, and would be dramatically improved by doing away with malaria. Fourth, doing away with malaria would allow people the energy to work on bettering their situation: malaria leaves you almost too weak to get across a room, and I had the benefits of health, youth, medicine, and good food. Fifth, long-term reliance on antimalarials can be lethal (a friend of mine died from liver problems after too many years on antimalarials, although the situation and his reaction were atypical).

keep those mosquito nets coming.

ScottW,

Maybe, but a healthier population has more energy and active hands to solve those problems. Malaria kills outright, but it also causes lifelong recurrent bouts of debilitating sickness. Healthy people have greater ability to raise their crops and clean their water.

jayackroyd -- pretty sure you're right -- that's why I said direct or indirect -- but I dunno whether it can be passed the way, say, hemorrhagic fever viruses can, or some STDs. IIRC there's an incubation period involved in the mosquito vector but ...

Eh, whatever. That's what wikipedia is for, I guess. The mathematical point stands though.

This is relatively good news. It appears to be the most effective clinical trial yet. But don't get your hopes up. The vaccine does not provide sterile immunity but should still save the lives of thousands of children. Since malaria is an arthropod borne disease, well over 90% of the population would need to be protected to have a significant effect on the transmission of the parasite. Malaria is going to be with us for decades to come.