Although the vaccine only protects about one-third of children who are immunized, those who get the shots are likely to have less severe cases of malaria. The parasitic disease kills about 435,000 people every year, the majority of them children under 5 in Africa.
"It's an imperfect vaccine but it still has the potential to save tens of thousands of lives," said Alister Craig, dean of biological sciences at the Liverpool School of Tropical Medicine, who was not linked to WHO or to the vaccine. Craig said immunizing the most vulnerable children during peak malaria seasons could spare many thousands of children from falling ill with malaria or even dying.
The vaccine, known as Mosquirix, was developed by GlaxoSmithKline and was approved by the European Medicines Agency in 2015. A previous trial showed the vaccine was about 30% effective in children who got four doses, but that protection waned over time. Reported side effects include pain, fever and convulsions.
WHO's Director-General Tedros Adhanom Ghebreyesus welcomed the new program, noting progress has "stalled and even reversed" in the ongoing fight against malaria. In the coming weeks, WHO said similar vaccination programs would begin in Kenya and Ghana together with other partners and that they aimed to reach about 360,000 children across the three countries. GSK is donating up to 10 million vaccine doses.
Other experts warned the vaccination programs should not divert limited public health funds from inexpensive and proven tools to curb malaria, like bednets and insecticides.
"This is a bold thing to do, but it's not a silver bullet," said Thomas Churcher, a malaria expert at Imperial College London. "As long as using the vaccine doesn't interfere with other efforts, like the urgent new for new insecticides, it is a good thing to do."
Craig noted one of health officials' biggest challenges could be convincing parents to bring their children for repeated doses of a vaccine that only protects about a third of children for a limited amount of time.
More commonly used vaccines, like those for polio and measles, work more than 90 percent of the time.
"This malaria vaccine is going to save many lives, even if it is not as good as we would like," Craig said. "But I hope this will kick-start other research efforts so that the story doesn't end here."