The malaria parasite, a notoriously deadly foe, has evolved countless ways to evade immune detection and thrive in human hosts. Mainly concentrated in sub-Saharan Africa, which accounts for roughly 95% of cases, malaria kills more than 600,000 people a year, a majority of them children younger than five years old. 

Last October, after years of development, the World Health Organization finally approved the world’s first vaccine to combat the deadly mosquito-borne disease. 

GlaxoSmithKline’s vaccine, known as RTS,S or Mosquirix, is not a particularly effective one. It requires three doses in children between five months and 17 months old, and a fourth dose given 12 to 15 months after that. Given to more than 800,000 children in Kenya, Malawi, and Ghana, the vaccine had an efficacy of about 50% against severe malaria in the first year, and its effectiveness dropped dramatically over time. 

Even so, public health officials are hailing the vaccine, which has been in testing since 1987, as a “game changer” in Africa. When combined with other malaria control measures, which include insecticide-treated bed nets and preventative drugs administered during the rainy season, it is expected to reduce malaria deaths by as much 70%, compared with the death rate in children given existing drugs.