Fri Oct 15, 2004 12:43 pm by Indy11
For the first time, researchers say, a vaccine against malaria has shown that it can save children from infection or death.
The vaccine, tested on thousands of children in Mozambique, was hardly perfect: It protected them from catching the disease only about 30 percent of the time and prevented it from becoming life-threatening only about 58 percent of the time.
But because malaria kills more than a million people a year, 700,000 of them children, even partial protection would be a public health victory. The disease, caused by a parasite carried by mosquitoes, is found in 90 countries, and drug-resistant strains are spreading.
Dr. Allan Schapira, strategy coordinator for the Roll Back Malaria campaign at the World Health Organization, said the trial was "good news, and definitely of great interest for malaria control."
The director of the Malaria Vaccine Initiative, which is underwriting tests on 15 experimental vaccines with money from the Bill and Melinda Gates Foundation, said the GlaxoSmithKline product tried in Mozambique was now its leading candidate and had proved that the concept worked.
"We'd all like to see the numbers be higher, absolutely," said Dr. Melinda Moree, director of the initiative. "But these are still very significant findings."
The results - to be published tomorrow in the British medical journal The Lancet - were comparable to or better than other methods of preventing infection in African villages, like distributing mosquito nets and insecticides, she said.
A malaria expert not connected with the study, Dr. Dyann Wirth, director of the Harvard Malaria Initiative, a program at the Harvard School of Public Health that is also seeking cures, was more cautious. She said the findings opened "a fruitful area for further investigation," but needed larger trials.
Glaxo and the Malaria Vaccine Initiative are planning such trials. But experts said it would be several years before the vaccine could be adopted as a childhood inoculation like those for diphtheria or measles. It is not yet known how long the vaccine's protection lasts, whether it is safe for infants and whether it is compatible with other vaccines.
A trial of the same vaccine among adults in Gambia six years ago showed that it protected about 35 percent of them from infection, but that the protection waned after about two months.
Still, experts noted that children stand to benefit more from a vaccine. In rural Africa, people can be infected several times a year. Children who survive to adulthood become immune. Newborns inherit some protection from their mothers, but it wears off in a few months. Young children are the hardest hit, and many who survive are brain-damaged.
The most recent vaccine test, conducted in two rural districts in southern Mozambique, where malaria is endemic during the six-month rainy season, involved 2,022 children ages 1 to 4. Half of them were given the malaria vaccine; rather than placebos, the other half got vaccines against hepatitis or bacteria that cause meningitis.
To ensure that the results were not skewed by other factors, the control and vaccine groups had roughly equal numbers of children who slept under mosquito nets at home and who lived near a clinic. The children were followed for six months and had home visits with blood and temperature checks at least once a month. Those who developed malaria were given immediate medical attention; the disease can kill in as little as 48 hours, but it can be cured if it is caught in time.
To test the vaccine's ability to prevent new infections, two subgroups of about 180 children each were given drugs to clear any parasites they might have had before the trial began. In both subgroups, most children developed new parasites. But the number was considerably smaller among those who had received the vaccine: 123 children in the vaccine group, compared with 159 in the control group. Over all, 11 vaccinated children developed severe malaria while 26 in the control group did.
Fifteen children died of various causes. None in the vaccine group died of malaria, while four in the control group did. Those numbers are too small to have any statistical meaning.
