The government of Malawi has begun administering the worlds first approved malaria vaccine to young children as part of a sweeping pilot program that could save tens of thousands of lives per year across some of Africas poorest regions, advocates say.

The World Health Organization announced the project Tuesday, saying children in Malawi, Kenya and Ghana would soon receive injections of the vaccine, known as RTS,S . The vaccine is the only one currently on the market, although inoculation only protects about a third of people from the mosquito-born disease. But RTS,S also shows significant overall reductions in severity for those who get the injection and end up contracting malaria anyways.

We have seen tremendous gains from bed nets and other measures to control malaria in the last 15 years, but progress has stalled and even reversed in some areas, Tedros Adhanom, the director-general of WHO, said in a statement.We need new solutions to get the malaria response back on track, and this vaccine gives us a promising tool to get there. The malaria vaccine has the potential to save tens of thousands of childrens lives.