There are more than 100 types of malaria parasite. The RTS,S vaccine targets the one that is most deadly and most common in Africa: plasmodium falciparum.

Trials, reported in 2015, showed the vaccine could prevent around four in 10 cases of malaria, three in 10 severe cases and lead to the number of children needing blood transfusions falling by a third.

However, there were doubts the vaccine would work in the real world as it requires four doses to be effective. The first three are given a month apart at five, six and seven months old, and a final booster is needed at around 18 months.

The findings of the pilots were discussed by two expert advisory groups at the WHO on Wednesday.

The results, from more than 2.3 million doses, showed:

• the vaccine was safe and still led to a 30% reduction in severe malaria
• it reached more than two-thirds of children who don't have a bed-net to sleep under
• there was no negative impact on other routine vaccines or other measures to prevent malaria
• the vaccine was cost-effective

"From a scientific perspective, this is a massive breakthrough, from a public health perspective this is a historical feat," said Dr Pedro Alonso, the director of the WHO Global Malaria Programme.

"We've been looking for a malaria vaccine for over 100 years now, it will save lives and prevent disease in African children." //

Having just seen the world develop Covid vaccines in record time, you might be wondering why it has taken so long with malaria?

Malaria is caused by a parasite which is far more insidious and sophisticated than the virus that causes Covid. Comparing them is like comparing a person and a cabbage.

The malaria parasite has evolved to evade our immune system. That's why you have to catch malaria time and time again before starting to get even limited protection.

It has a complicated life cycle across two species (humans and mosquitoes), and even inside our body it morphs between different forms as it infects liver cells and red blood cells.

Developing a malaria vaccine is like nailing jelly to a wall and RTS,S is only able to target the sporozoite form of the parasite (this is the stage between being bitten by a mosquito and the parasite getting to the liver).

It is why the vaccine is 'only' 40% effective. However, this is still a remarkable success and paves the way for the development of yet more potent vaccines.