KAMPALA, Uganda (AP) — Health authorities in Kenya have started administering doses of the world’s first licensed malaria vaccine to young children in rural areas facing high transmission rates.

Kenya on Friday becomes the third African country to introduce the vaccine, after Malawi and Ghana.

Kenya’s health ministry describes the milestone on Twitter as “a historic day” for the East African country as the health minister launches vaccinations in remote Homa Bay county.

Malaria is a top killer in many African countries. The parasitic disease kills about 435,000 people every year, the majority of them children under 5 in Africa.