Most vaccines are against viruses and bacteria. Malaria is a more complicated organism, a protist with many local varieties, and a tremendous ability to evolve around vaccines and medications in general.
Natural immunity to malaria is often limited to the local variant -- go a couple hundred miles, and you have no resistance at all. Vaccines rely on the body's natural immune system, so it is nearly impossible to create a single vaccine that is effective across the world.
For this reason, I'm highly skeptical that this initial test result will hold up with broader trials. BTW my spouse is a malariologist, formerly at WHO, and I've been a witness to much of the fight against malaria over the years.
From what i read elsewhere it works almost like a magic without producing resistance, and i'm wondering what would be the first hand account of a practitioner.
There's already artemisinin resistance starting in several places around the world, especially the Thai-Cambodia border, a very chaotic area with high endemic malaria.
The main problem is that cheap medications are often out of date or have improper dosage. Also, people stop taking medication when they feel better, but before the parasite is eliminated. The result is resistant parasites survive the treatment, and then spread.
We have maybe a decade of artemisin usability in the hottest areas. Could be more or less depending on how efficient public health practices are. But no way is it a permanent cure.
The artemisinin resistance is very scary. Cambodia is where Chloroquine resistance developed, which has since spread to Africa. If artemisinin resistance were to become widespread too, it would be a disaster. Containing it is a very tough problem, but there are efforts underway to try. One of the members of my lab is traveling to the area soon to test a new screening method.
thanks, i see. With developing resistance and being cheap, i wonder whether the artemisinin would fall off the radar of the industry - i mean it has shown good cancer cell killing efficiency and selectivity in tissue samples and mice, yet i haven't heard about serious research beyond that.
Smallpox was eliminated through a vaccine campaign. Resistance against vaccines is generally different from resistance from treatments. For example, since vaccines are in place pre-infection, the amount of target microbes in the body at time of action is pretty low, giving a much higher chance of killing them all. Treatment is usually given after infection, where there will be a large amount of target microbes. This will substantially increase the probability some critter surviving with more resistance genes and then passing them on.
There's a lot of complexity here I'm going to attempt to simplify. Apologies in advance if I glossed over any important details.
It all starts with what Malaria has evolved to do. The lifecycle of malaria requires both a mosquito and a human. It gets into a female mosquito, hangs out in her gut until she bites a human, jumps into the human and hangs out there for a while mucking about, and then jumps back to a different mosquito.
If malaria straight-up killed its host, it wouldn't transmit itself on to the next one. This means malaria must be really good at two things: keeping its host walking around and going undetected for as long as possible. It has lots of tricks it uses to stay under the radar. This all makes sense because the longer it can stay in the host, the more likely it'll get picked up by something else. Think of malaria like a spy that's infiltrated your population. You know one of your civilians is killing the others, but you can't figure out who.
It's also important to know HOW vaccinations work. There are four golden strategies used today:
- Put a dead bugger in the body.
- Put a neutered bugger in the body.
- Put the bugger's coat (a virus-like particle) in the body.
- Put the bugger's perfume (a protein marker) in the body.
All four of these strategies work the same way. Your body recognizes an intruder and teaches itself how to eliminate the threat.
We've established that malaria is good at going undetected. This renders the first two strategies ineffective. Even if we did introduce dead/neutered malaria into the body, the body will still have a hard time finding it when real Malaria enters the system.
We can't use the third strategy because Malaria isn't a virus. That leaves us with only one option: a perfume (subunit) vaccine.
A subunit vaccine is a vaccine where you take the perfume of a bugger and give it to the body saying "Anything that smells like this, you should probably deal with". These are difficult vaccines to put together. Proteins, like perfume, are a carefully constructed thing and are hard to perfectly replicate. Plus, given their complex nature, the body can get confused and build ineffective defenses since it's only given a protein to work with.
On top of all this, the malaria bugger goes through three different stages of its life while in the human body. If you target it late stage, you'll prevent further transmission but the human could still die. You want to target it early stage, preventing transmission AND protecting the human from symptoms. Unfortunately, your body only has 5 minutes from being bitten to to find the bugger and kick its ass before he effectively vanishes from sight.
So where does that leave us? We have a spy entering our country. We are already doing everything we can to destroy his transit before he enters our borders (spraying with DEET to kill mosquitos). We need to catch him before he masquerades as a citizen, otherwise we will never find him. So our only option is to look for signs of a spy and ruthlessly eliminate anything that fits the bill.
That's what RTS,S/AS01 does. In the 80s we were able to produce a protein from the malaria sporozoite (the first stage inside the human body) to get a small level of immunity in humans. The problem since then has been ramping up the immune response. The body needs to act fast (within 5 minutes of being infected) and with extreme prejudice (wiping out the sporozoites) off of very little training (a single sporozoite protein). Vetting this vaccination is also tricky, since it requires human field testing in Africa.
In other words, this vaccine is the culmination of 50 years of dedication, research, and hard work. It's also a miracle of modern science. Most importantly, it will save a LOT of human lives.
Many thanks for the explanation. You sound like a teacher; I feel like I've really learned something this morning.
Quick question: is there an issue with resistance when it comes to vaccinations? I understand the problem with creating better combative medicines is working out how to attack the critters before they produce resistance. Either way, it sounds like a profound breakthrough for affected countries.
Most diseases on the same scale as malaria were effectively wiped out by vaccination, because social pressure to get rid of them was tremendously high. The same would probably apply with malaria: vaccination programs would be so immediate and massive to give it very little chance of mutating quick enough to maintain the current (massive) level of infection. Even a reduction of 70 or 80% would make an incredible difference.
The only real problem will be price. GSK will want a lot of money, and most malaria-affected countries are poor. Chances are that the "developed world" will have to step in and sponsor vaccination programs to the tune of billions, making (mostly African and South-Asian) countries even more dependent on them that they are now. Some of them had just managed to get rid of old debts, and now they'll have to make new ones. I expect the debate on pharmaceutical patents will flare up again.
For starters surviving malaria does not prevent you from getting it again. So a vaccine has to be more effective in creating an immune response than the actual parasite.
