The world’s first malaria vaccine is being rolled out in Kenya from Friday.
It is the third African country to take part in the scheme after Ghana and Malawi.
Across the three countries, more than 300,000 children under the age of two are expected to be given the vaccine each year.
The RTS,S vaccine has been 30 years in the making, and it works by training the immune system to attack the malaria parasite, which is spread by mosquito bites.
Earlier smaller trials showed that nearly four in 10 babies aged between the ages of five and 17 months, who received all four doses of the vaccine, were protected.
The World Health Organization (WHO) says this could be a game changer, but says the vaccine needs to be used alongside bed nets and insecticides.
Malaria kills more than 400,000 people a year – more than half of them children in sub-Saharan Africa.