Dramatic new results from a malaria vaccine have raised hopes that the world might be on the verge of defeating a disease that kills nearly 800,000 people every year.
If confirmed by future trials, it could be a breakthrough: the world's first successful vaccine against a human parasite, and a major blow against a disease that affects some 225 million people annually, killing primarily poor African children.
Progress against malaria, one of the world's deadliest diseases, has been gaining momentum in recent years. A new study by the World Health Organization predicts that, within a decade, malaria could be eradicated from one-third of the 108 countries where it is now endemic. Malaria deaths have dropped by 20 per cent in the past 10 years.
The first large-scale trials of the new vaccine, involving more than 15,000 children across seven African countries, show that it cuts the risk of malaria in half. If all goes well, it could become available within four years and it would probably be included with routine immunizations for infants.
There are still key questions that need to be answered, including the cost of the vaccine and its effectiveness over longer periods, especially for infants, since the trial results for the youngest infants have not yet been reported. But the manufacturer, British company GlaxoSmithKline, has pledged that the product will be sold for its factory cost, plus a "small return" that will be reinvested in research on second-generation vaccines.
"It's been a long time coming, and indeed we are still not there yet, but it is becoming increasingly clear that we really do have the first effective vaccine against a parasitic disease in humans," the New England Journal of Medicine said in an editorial on Tuesday.
It said the vaccine was "a great achievement and an important advance," but it also cautioned that there are key questions about the duration of the vaccine's protective effect, and whether its effectiveness is weakened by the intensity of the disease's transmission.
Vaccines for HIV and malaria have been two of the holy grails of medical research for decades, and both have been huge and frustrating challenges. Researchers have been working for more than 20 years to develop the latest malaria vaccine, known as RTS,S. More than $500-million has been invested in the project.
"Sadly, many people have resigned themselves to malaria being a fact of life in Africa," said Tsiri Agbenyega, a principal investigator in Ghana for the latest trials. "This need not be the case."
Canadian malaria expert Kevin Kain, who helped in early field trials of a precursor of the vaccine in the 1990s, said the latest results are "a pretty impressive landmark" in the fight against malaria. He noted, however, that the vaccine's effectiveness rate of 50 per cent is far lower than other vaccines such as those for hepatitis, which are more than 90-per-cent effective. This could damage the acceptance level for the vaccine in some communities, he said.
"It's an advance, but it's not anything close to the protection that we're used to getting from other vaccines," said Dr. Kain, who is director of Sandra A. Rotman Laboratories at the McLaughlin-Rotman Centre for Global Health in Toronto. "Malaria is a formidable enemy, and it's dangerous to underestimate it."
Still, even with 50-per-cent effectiveness, the vaccine could be a tremendous benefit to public health, providing a huge reduction in social and medical costs in African countries, he said. By some estimates, malaria is responsible for 40 per cent of public-health costs in sub-Saharan Africa and it causes up to 50 per cent of hospital admissions.
The trials found that the vaccine is up to 56-per-cent effective for some forms of malaria. But for the most severe form of malaria, which causes most deaths, the vaccine was found to be 35-per-cent effective. Still, it has the potential to prevent millions of cases of malaria in the future, researchers say.
Massive investments in anti-malaria programs, including the large-scale distribution of mosquito nets and greater access to anti-malaria drugs, have begun to pay off dramatically in recent years. The number of annual deaths from malaria has fallen from 985,000 a decade ago to about 780,000 in 2009.
In the past four years alone, malaria has been eradicated from three countries: Morocco, Armenia and Turkmenistan. And at the current rate of progress, malaria deaths could be reduced by three million in the next four years, according to the WHO study.