A large-scale trial of what has been called the world's first malaria vaccine to give partial protection to children is due to start in Malawi, reports BBC.
The RTS,S vaccine trains the immune system to attack the malaria parasite, which is spread by mosquito bites.
Earlier, smaller trials showed that nearly 40 per cent of the 5-to-17-month-olds who received it were protected.
Malaria cases appear to be on the rise again after a decade of success in combating the deadly disease.
According to the most recent annual figures, global malaria cases are no longer falling, sparking concerns about its resurgence.
More than 90 per cent of both those who were infected and the 435,000 who died were in Africa. Children are particularly vulnerable.
Malawi, which recorded nearly five million confirmed cases in 2017, has been chosen, along with Kenya and Ghana, to be used in the large-scale pilot of the RTS,S vaccine.
Three-decade development
The countries were picked because they already run large programmemes to tackle malaria, including the use of bed nets, yet still have high numbers of cases.
The vaccine has been more than three decades in the making, with scientists from drugs company GSK creating it in 1987.
Years of testing supported by a host of organisations, including the Path Malaria Vaccine Initiative, and costing an estimated $1bn (£770m) have led to this point. This latest phase is being co-ordinated by the World Health Organization (WHO), which says the vaccine is the first to provide some protection to children.
The nearly 40 per cent efficacy is not high in comparison with vaccines for other diseases, but the WHO says RTS,S will add to the preventative measures, such as bed nets and insecticides, already being used.
