The World Health Organization announced this week that Malawi has become the first country to begin immunizing children against malaria. WHO officials say the country is using the only approved vaccine to protect against the mosquito-spread disease.
The Associated Press says the vaccine protects about one-third of children who receive it. But those who get the shots are likely to have a less severe case of malaria.
The disease kills about 435,000 people every year. In Africa, most of the victims are children under the age of 5.
"It's an imperfect vaccine but it still has the potential to save tens of thousands of lives," notes Alister Craig. He is with the Liverpool School of Tropical Medicine in Britain. He added that immunizing the most at-risk children during peak malaria seasons could prevent thousands from getting sick or even dying.
Craig is not linked to the malaria vaccine or the WHO.
The vaccine, known as Mosquirix, is a product of the British drug company GlaxoSmithKline. It was approved by the European Medicines Agency in 2015.
An earlier test showed the vaccine was about 30 percent effective in children who got four shots, but that protection weakened over time. Reported side effects include pain, high body temperatures and severe shaking.
Pedro Alonso is head of the WHO's malaria program. He says similar vaccination programs would begin in the coming weeks in Kenya and Ghana. The aim is to vaccinate about 360,000 children each year across the three countries.
Alonso called the vaccination campaign a "historical moment." He noted that it is much more difficult to design a vaccine against a parasite – an organism living in or on another organism – as opposed to a bacterium or virus.
Alonso admitted the malaria vaccine does have problems. But he said the world could not wait any longer for a better version.
"We don't know how long it will take to develop the next-generation vaccine," he said. "It may be many, many years away."
He said the slowed progress against malaria demands new tools now. Resistance is growing to medicines that treat the disease. And mosquitoes are becoming more resistant to insecticides. In addition, money used for fighting malaria has not been increasing in recent years.
It took GlaxoSmithKline (GSK) and partners more than 30 years to develop the vaccine, at a cost of around $1 billion. A company spokesperson said GSK is working with partners to raise money for even larger vaccination programs.
Some experts say the vaccine should not take away from other efforts that offer non-costly, proven ways to reduce malaria. They note examples such as the use of bed nets around sleeping areas and insecticide products.
"This is a bold thing to do, but it is not a silver bullet," said Thomas Churcher, a malaria expert at Imperial College London. A "silver bullet" is an overly simple and immediate answer to a complex problem.
Churcher added, "As long as using the vaccine doesn't interfere with other efforts, like the urgent need for new insecticides, it is a good thing to do."
Alister Craig noted that one difficulty could be persuading 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."
I'm Anna Matteo.
The Associated Press reported this story. Ashley Thompson adapted it for VOA Learning English. George Grow was the editor.
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immunize - v. to give (someone) a vaccine to prevent infection by a disease
mosquito - n. a small flying insect that bites the skin of people and animals and sucks their blood
moment - n. a very short period of time
dose - n. the amount of a medicine, drug, or vitamin that is taken at one time