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.