Malaria vaccine approved by WHO
African children to benefit the most
GENEVA: The World Health Organization on Wednesday endorsed the first vaccine to prevent malaria, debuting a tool that could save the lives of tens of thousands of children in Africa each year.
Malaria is among the oldest known and deadliest of infectious diseases. It kills about 500,000 people each year, nearly all of them in sub-Saharan Africa — among them 260,000 children younger than 5.
The new vaccine, made by GlaxoSmithKline, rouses a child’s immune system to thwart Plasmodium falciparum, the deadliest of five malaria pathogens and the most prevalent in Africa. The vaccine is not just a first for malaria; it is the first developed for any parasitic disease.
In clinical trials, the vaccine had an efficacy of about 50% against severe malaria in the first year but dropped close to zero by the fourth year. And the trials did not measure the vaccine’s impact on preventing deaths, which has led some experts to question whether it is a worthwhile investment in countries with countless other intractable problems.
But severe malaria accounts for up to half of malaria deaths and is considered “a reliable proximal indicator of mortality,” said Dr Mary Hamel, who leads the WHO’s malaria vaccine implementation program. “I do expect we will see that impact.”
A modelling study last year estimated that if the vaccine were rolled out to countries with the highest incidence of malaria, it could prevent 5.4 million cases and 23,000 deaths in children younger than 5 each year.
And a recent trial of the vaccine in combination with preventive drugs given to children during high-transmission seasons found that the dual approach was much more effective at preventing severe disease, hospitalisation and death than either method alone.
To have a malaria vaccine that is safe, moderately effective and ready for distribution is “a historical event”, said Dr Pedro Alonso, director of the WHO’s global malaria program.
Parasites are much more complex than viruses or bacteria, and the quest for a malaria vaccine has been under way for 100 years, he added. “It’s a huge jump from the science perspective to have a first-generation vaccine against a human parasite,” he said.
The malaria parasite is a particularly insidious enemy because it can strike the same person over and over. In many parts of sub-Saharan Africa, even those where most people sleep under insecticide-treated bed nets, children have on average six malaria episodes a year. Even when the disease is not fatal, the repeated assault on their bodies can leave them weak and vulnerable to other pathogens, permanently altering the immune system.
Malaria research is littered with vaccine candidates that never made it past clinical trials. Bed nets, the most widespread preventive measure, cut malaria deaths in children younger than 5 by only about 20%. Against that backdrop, the new vaccine, even with modest efficacy, is the best new development in the fight against the disease in decades, some experts said.
“Progress against malaria has really stalled over the last five or six years, particularly in some of the hardest-hit countries in the world,” said Ashley Birkett, who heads malaria programs at PATH, a nonprofit organization focused on global health. With the new vaccine, “there’s potential for very, very significant impact there,” he said.
Called Mosquirix, the new vaccine is given in three doses between ages 5 and 17 months, and a fourth dose roughly 18 months later. Following the clinical trials, the vaccine was tried out in three countries — Kenya, Malawi and Ghana — where it was incorporated into routine immunisation programs.
More than 2.3 million doses have been administered in those countries, reaching more than 800,000 children. That bumped up the percentage of children protected against malaria in some way to more than 90% from less than 70%, Ms Hamel said.
“The ability to reduce inequities in access to malaria prevention — that’s important,” she said. “It was impressive to see that this could reach children who are currently not being protected.”